The interpretation timeline
2 Timothy 2:5 Douay-Rheims

For he also that striveth for the mastery, is not crowned, except he strive lawfully.

A.D. 379 – 1871 10 witnesses 12 excerpts

Patristic

before A.D. 750
379
A.D.
Basil of Caesarea Patristic
c. A.D. 330–379
“But, if you place yourself in the hands of a man rich in virtue, you will become the heir of the good qualities he possesses and you will be supremely blessed with God and men. On the other hand, if, to spare the body, you seek a master who will condescend or, rather, degrade himself to the level of your vices, all in vain did you endure the struggle of renunciation, since you have surrendered yourself to a life of gratifying your passions by choosing a blind guide who will lead you into the pit.”
Source
date
unknown
c. A.D. 380
“For in the present world the righteous and the wicked are mingled together in the common affairs of life, but not in holy communion: and in this the friends and favourites of God are guilty of no sin. For they do but imitate "their Father which is in heaven, who maketh His sun to rise on the righteous and unrighteous, and sendeth His rain on the evil and on the good;" and the righteous man undergoes no peril on this account. For those who conquer and those who are conquered are in the same place of running, but only those who have bravely undergone the race are where the garland is bestowed; and "no one is crowned, unless he strive lawfully." For every one shall give account of himself, and God will not destroy the righteous with the wicked; for with Him it is a constant rule, that innocence is never punished.”
Source
395
A.D.
Gregory of Nyssa Patristic
c. A.D. 335–395
“How can there be a lawful contest if there is no opponent? If there is no opponent, there is no crown. Victory does not exist by itself, without there being a defeated party.”
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“What is the world but a sort of arena of continual strife? Wherefore also in the Apocalypse the Lord says, "To him that overcometh will I give a crown of life;" and Paul says, "I have fought a good fight;" and in another place, "No man is crowned except he strive lawfully." He who institutes this combat is Almighty God. Now he who in this world offers a combat, does he not first provide all things which are necessary thereto, and prepare the chaplets of victory before he summons the athletics to contend for the prize; and all this that the conqueror may not suffer delay, but retire from the contest crowned with his reward? Now the rewards of man are the fruits of the earth and the lights of heaven; the former for the use of this present life, the latter for the hope of life eternal. As a wrestler therefore he enters the lists last of all... It is he therefore who poises the blow, but it is Christ Who strikes, it is he who lifts up his heel, but Christ Who directs it to the ground... by the preaching of Christ he wounded those evil spirits which assaulted him. Rightly therefore did man, for whom a race was prepared, enter the course last, that he might be preceded by heaven which was to be, as it were, his reward.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“You say that her clothes are shabby, but virginity resides not in clothing nor in one's complexion but in the body and soul. Is it not strange that we have different standards? We will not judge the philosopher by his hair or his staff or his tunic but by his way of life, his character and soul. The soldier too we will not approve for his mantle or belt but for his strength and manliness. Yet the virgin, who represents a state so admirable and superior to all others, we will simply and offhandedly assume practices her virtue because of the squalor of her hair, her dejected look and gray cloak. We do not strip her soul bare and scrutinize closely its inner state. But he who has drawn up the rules for this contest does not permit this. He orders that those who have entered not be judged by their clothing but by the convictions of their souls. "Athletes," Paul says, "deny themselves all sorts of things," anything that would trouble the health of the soul. "If one takes part in an athletic contest, he cannot receive the winner's crown unless he has kept the rules." What, then, are the laws of this contest? Hear again his words, or rather Christ himself, who has established the contest: "The virgin is concerned with things of the Lord, in pursuit of holiness in body and spirit."”
Source
“And, in a word, it is ever necessary that he who would please God and become approved and holy should not lead an easy, free, and dissolute life, but a laborious life, full of hardship and toil. For "no man," it is said, "is crowned except he strive lawfully," and in another place, "Every man that striveth for the mastery is temperate in all things." He abstains from evil words and looks, from base conversation and slander, and from blasphemy and evil speaking. From this we learn that, though trial may not come upon us from any external source, it is our duty to exercise ourselves each day in fasting, self-denial, moderate diet, and a plain table, avoiding extravagance in any way. Otherwise we cannot please God.”
Source
“"And if a man also strive for masteries, yet is he not crowned except he strive lawfully." These things are said indeed to Timothy, but through him they are addressed to every teacher and disciple. Let no one therefore of those who hold the office of a Bishop disdain to hear these things, but let him be ashamed not to do them. "If any one strive for masteries," he says, "he is not crowned, except he strive lawfully." What is meant by "lawfully"? It is not enough that he enters into the lists, that he is anointed, and even engages, unless he comply with all the laws of the exercise, with respect to diet, to temperance and sobriety, and all the rules of the wrestling school, unless, in short, he go through all that is befitting for a wrestler, he is not crowned. And observe the wisdom of Paul. He mentions wrestlers and soldiers, the one to prepare him for slaughter and blood, the other with reference to endurance, that he might bear everything with fortitude, and be ever in exercise.”
Source
435
A.D.
John Cassian Patristic
c. A.D. 360–435
“One who wants to extinguish the natural desires of the flesh should first hasten to overcome those vices whose ground is contrary to our nature. For if we desire to test out the force of the apostle's counsel, we ought first to learn what are the laws and what the discipline of the world's contest. This is so that finally by a comparison with these, we may be able to know what the blessed apostle meant to teach to us who are striving in the spiritual contest.”
Source

Scholastic

c. 1100 – 1500
1273
A.D.
Thomas Aquinas Catholic
1225–1274
“Above he led Timothy to diligent preaching of the Gospel; here he leads him to constant endurance of martyrdom. And first he leads him to sustain suffering for the salvation of the faithful; second he teaches him how he should resist unbelievers, at "do not with words." Again, first the preparation for enduring martyrdom is set forth; second, the exhortation to martyrdom, at "be mindful." The preparation for martyrdom is set forth as to three things. The first is fortitude of soul; the second is the dispensing of goods, at "and what you have heard"; the third is the fruitful labor of warfare, at "labor." Now fortitude is required for martyrdom, which concerns the dangers of death. And therefore he says "you therefore, my son" — namely, whom I have begotten through the Gospel — "be strengthened in grace." Ps. XXX, v. 24: "Act manfully, and let your heart be strengthened." Which is not in you — namely, whose strength is vain — but in Christ Jesus. Eph. c. VI, 10: "Be strengthened in the Lord, and in the might of his power." Or "in grace," etc., that is, in the free gift of God through Christ. Io. I, 17: "Grace and truth was made through Jesus Christ." The second is the dispensing of goods. Concerning which it must be noted that when someone is brought to death, he disposes of his own things. Therefore the saints ought to be no less solicitous about the spiritual goods entrusted to them, that these not perish after their death, but that they entrust them to others; and therefore he warns him that, if he should come to martyrdom, he should dispense the teaching of the faith. And first he states how he received it, namely through hearing; hence he says "what you have heard from me," and I from Christ. And I say "from me" not singularly, but confirmed through many witnesses, that is, through the law and the prophets. Rom. III, 21: "witnessed by the law and the prophets." Or through the apostles. I Cor. XV, 11: "For whether I, or they, so we have preached, and so you have believed." "Commend these things," inasmuch as they have been received. Sap. VII, 13: "which I have learned without deceit, and communicate without envy." "To faithful men" — namely so that they should not seek temporal gain, but the glory of God. I Cor. IV, 2: "Here now it is required among stewards, that a man be found faithful." Matthaeus XXIV, 45: "a faithful and prudent servant, whom the lord has set over his household," et cetera. Again, it must be those who are fit for dispensing; therefore he says "who fit," et cetera. Now they ought to be fit in three ways. First in understanding, that they be wise in understanding. Lc. XXI, 15: "I will give you a mouth and wisdom," et cetera. Again in tongue, that they be eloquent in teaching. Is. l, 4: "The Lord has given me a learned tongue, that I should know how to raise up by a word him who has fallen." Again in work, for "Jesus began to do and to teach," Act. I, 1. Then when he says "labor," the third is set forth, which is the lawful labor of warfare, to which he first exhorts; second he sets forth the reward of the labor, at "for indeed he who"; third, the wages of warfare, "him who labors." Again, first he exhorts to lawful labor; second he explains what labor is lawful, at "no one." He therefore says "labor as a good soldier of Christ." Now one is a soldier of Christ in three ways. First, insofar as he fights against sins. Iob VII, 1: "The life of man upon earth is a warfare"; and XIV, 14: "All the days in which I now war, I wait," et cetera. And this fight is against the flesh, the world, and the devil. Eph. ult.: "Our wrestling is not against flesh and blood," et cetera. Second, one is a soldier of Christ by fighting against errors. II Cor. X, 4: "The weapons of our warfare are not carnal, but mighty to God, destroying counsels unto the destruction of fortifications," et cetera. Third is the warfare of martyrs against tyrants. And this is more laborious. Iob XXV, 3: "Is there any numbering of his soldiers?" And a soldier ought not to rest, for he is so called from having to sustain warfare. Then when he says "no one," he explains what lawful labor is. And first he leads him to labor; second he shows what sort the good soldier ought to be, at "that he may please him." First, concerning the first he does two things: he sets forth an example; second he makes it clear. He therefore says "no one warring for God," et cetera. Concerning the first it must be known that the end of spiritual warfare is one thing, and the end of bodily warfare is another; for the end of bodily warfare is that one obtain victory against the enemies of the fatherland, and therefore soldiers ought to abstain from those things which draw them away from the fight, namely from business and delights. I Cor. IX, 25: "He who strives in the contest abstains from all things." But the end of spiritual warfare is that they have victory over men who are against God; and therefore it is fitting that they abstain from all things which draw them away from God. Now these are secular affairs, for the anxiety of this age chokes the word. And therefore he says "entangles himself." But on the contrary: secular affairs are temporal, yet the apostle did this, when he lived by the labor of his own hands. I respond. It must be said that the apostle says "entangles," and does not say "exercises." Now he is entangled by these things, whose care and anxiety is joined about them. And then properly these very things are forbidden to the soldiers of Christ, in which it is shown that the mind need not be entangled. Again, he does not say simply "is entangled," but says "entangles himself," because sometimes one is entangled, and does not entangle himself. For he entangles himself when he takes up affairs without piety and necessity; but when the necessity of an office of piety and authority is exercised, then he does not entangle himself, but is entangled by such necessity. Rom. XVI, 2: "that you assist him in whatever business he shall need of you." Now the reason why they ought not to entangle themselves is "that he may please him to whom he has proved himself." I Io. II, 15: "If anyone loves the world, the charity of the Father is not in him." For he who is a soldier of Christ has devoted himself to warring for God; and therefore he ought to strive that he may please him to whom he has devoted himself. Then when he says "for indeed he who," he sets forth the reward of the labor. And because someone might say: O Paul, you impose great things, but what is the fruit of these things? He responds: take an example from secular contests, where not all, but those who fight lawfully receive the crown. So therefore it will also be in spiritual things, that no one will be crowned, unless he keeps the due laws of the fight. I Cor. c. IX, 25: "They indeed that they may receive a corruptible crown, but we an incorruptible one." Sap. c. IV, 2: "Crowned, she triumphs forever." Then when he says "him who labors," he shows the wages, and forbids him secular affairs. And first he sets forth the wages under a metaphor; second he explains, at "understand." For the office of preachers and teachers is the office of soldiers, insofar as they rise up against enemies and vices; likewise of farmers, insofar as they produce fruit by advancing men to good things. Of this the field is the Church, and the principal farmer is God, working inwardly and outwardly. Io. XV, 1: "I am the true vine, and my Father is the farmer." But men apply their ministry outwardly. I Cor. III, 6: "I planted, Apollo watered, but God gave the increase." These are the outward farmers. Iob c. XXXI, 39: "if I have afflicted the soul of its farmers." This farmer, therefore, ought to receive fruit; the fruits of this are the works of the virtues. Eccli. XXIV, 23: "My flowers are the fruit of honor and honesty." Gal. V, 22: "But the fruit of the spirit is charity, joy, peace, patience." Among these fruits are also the fruits of alms. Act. IX, 36: "she was full of good fruits and of alms which she did." These, therefore, ought principally to receive the fruit, that they themselves may rejoice. First, concerning the fruits of their subjects. Phil. IV, 1: "therefore, my dearest and most longed-for brothers, my joy and my crown." Second, concerning temporal subsidies, not as the principal reward, but as wages. Gal. VI, 6: "But let him who is instructed in the word share with him who instructs him, in all good things." Matth. c. X, 10: "The laborer is worthy of his food." Then when he says "understand," he explains what he had said, following the manner of Christ after parables. Matth. XIII, 9: "He who has ears to hear, let him hear." As if he were to say: reduce these things to spiritual understanding. Dan. X, 1: "understanding is needed in the vision." As if someone might say: you say, "receive wages," O Timothy; but you yourself do not do this, since you wish to live by the labor of your hands. Hence "understand what I say," for discretion is necessary, since wages are not to be received where there is occasion of avarice against the Gospel, or on account of covetousness, or on account of idleness. And this you will be able to understand, for "he will give," et cetera. I Io. II, 27: "The anointing will teach you concerning all things."”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“And if a man also strive for masteries,.... In the Olympic games, by running, wrestling, leaping, &c. yet is he not crowned; with a corruptible, fading crown, a crown made of herbs and leaves of trees, as parsley, laurel, &c. except he strive lawfully; according to the laws and rules fixed for those exercises; so no man that calls himself a Christian, minister, or any other, can expect the crown of life, the prize of the high calling of God, except he runs the race set before him, in the right way; looking to Christ, the mark, pressing through all difficulties, towards the prize, and holds on and out unto the end.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“If a man also strive for masteries - Εαν δε και αθλῃ τις· If a man contend in the public games - the Olympic or Isthmian games among the Greeks, so often alluded to and particularly explained in the notes on Co1 9:24-26, to which the reader is referred for a full illustration of this verse. Is he not crowned - Though he may have conquered, except he strive lawfully - unless he enter according to the rules of the athlete, and act as these direct. No man, however zealous he may have been, is to expect the Well done, good and faithful servant, from Jesus Christ, unless he have labored in the word and doctrine, preached the truth as it is in Jesus, and built up the Church upon Him who is its only Foundation.”
Source
1871
A.D.
1871
“And--"Moreover." strive for masteries--"strive in the games" [ALFORD]; namely, the great national games of Greece. yet is he not crowned, except--even though he gain the victory. strive lawfully--observing all the conditions of both the contest (keeping within the bounds of the course and stript of his clothes) and the preparation for it, namely, as to self-denying diet, anointing, exercise, self-restraint, chastity, decorum, &c. (Co1 9:24-27).”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.