The interpretation timeline
John 4:42 Douay-Rheims

And they said to the woman: We now believe, not for thy saying: for we ourselves have heard him, and know that this is indeed the Saviour of the world.

A.D. 407 – 1849 7 witnesses

Patristic

before A.D. 750
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“(Hom. xxxv. 1) The Jews disbelieved in spite of miracles, while these exhibited great faith, before even a miracle was wrought, and when they had only heard our Lord’s words. And many more believed because of His own word. Why then do not the Evangelists give these words? To shew that they omit many important things, and because the result shews what they were; the result being that the whole city was convinced. On the other hand, when the hearers are not convinced, the Evangelists are obliged to give our Lord’s words, that the failure may be seen to be owing to the indifference of the hearers, not to any defect in the preacher. And now, having become Christ’s disciples, they dismiss their first instructor; And they said unto the woman, Now we believe not because of thy saying: for we have heard Him ourselves, and know that this is indeed the Christ, the Saviour of the world. How soon they understand that He was come for the deliverance of the whole world, and could not therefore confine His purposes to the Jews, but must sow the Word every where. Their saying too, The Saviour of the world, implies that they looked on this world as miserable and lost; and that, whereas Prophets and Angels had come to save it, this was the only real Saviour, the Author not only of temporal but eternal salvation. And, observe, whereas the woman had spoken doubtfully, Is not this the Christ? they do not say, we suspect, but we know, know, that this is indeed the Saviour of the world, not one Christ out of many. Though they had only heard His words, they said as much as they could have done, had they seen ever so many and great miracles.”
Source
430
A.D.
Augustine of Hippo Patristic
A.D. 354–430
“(Tr. xv. c. 33) So then they knew Christ first by report of another, afterwards by His own presence; which is still the case of those that are without the fold, and not yet Christians. Christ is announced to them by some charitable Christians, by the report of the woman, i. e. the Church; they come to Christ, they believe on Him, through the instrumentality of that woman; He stays withthem two days, i. e. gives them two precepts of charity. And thenceforth their belief is stronger. They believe that He is indeed the Saviour of the world.”
Source

Scholastic

c. 1100 – 1500
1270
A.D.
Thomas Aquinas Catholic
1225–1274
“Above, the Lord foretold to the apostles the fruit which had come to the Samaritans from the woman's preaching; but here the Evangelist deals with this fruit, and first the fruit arising from the woman's preaching is set forth; second, the increase of this fruit brought about through Christ is intimated, at the place, "And many more believed in him because of his word." Now the fruit arising from the woman's preaching is shown with regard to three things. First, with regard to faith, in that they believed in Christ; hence he says, "Now from that city" — namely the one to which the woman had gone — "many of the Samaritans believed in him," and this on account of the word of the woman, from whom Christ had asked for water, bearing witness — namely, that "he told me all things whatsoever I have done": which testimony indeed was sufficiently inducing them to believe in Christ. For since the things which Christ had said pertained to the manifestation of her own faults, unless she herself had been moved to believe, she would not have reported such things; and therefore, as soon as they heard her words, they believed. In this it is signified that faith is from hearing. Second, the fruit is shown with regard to their approach to Christ: for from faith follows the desire of the thing believed. And therefore, after they believed, they approach Christ, that they might be perfected through him; hence he says, "When the Samaritans had come to him." Psalm 33:6: "Come to him, and be enlightened." Matthew 11:28: "Come to me, all you who labor and are burdened, and I will refresh you." Third, with regard to desire: for it is necessary for the believer not only to come to Christ, but also to have him with him; hence he says that they asked him to stay there. "And he stayed there two days." Now the Lord remains with us through charity. Below, 14:23: "If anyone loves me, he will keep my word"; and a little after: "and we will make our dwelling with him." But he stays two days, because there are two precepts of charity, namely the love of God and of neighbor, on which "the law and the prophets depend," as is said in Matthew 22:40. But the third day is the day of glory: Hosea 6:3: "He will give us life after two days; on the third day he will raise us up." And on this day he did not stay there, because the Samaritans were not yet capable of glory. Consequently, when he says, "And many more believed in him because of his word," the Evangelist sets forth that the fruit arising from the woman's preaching was increased by the presence of Christ; and this in three ways. First, from the multitude of believers; second, from the manner of believing; third, from the truth of the faith. It was increased from the multitude of believers, because on account of the woman many believed in him; but many more believed on account of his word, namely Christ's. In this it is signified that although many believed through the prophets, yet many more were converted to the faith when Christ came, according to that word of Psalm 7:8: "Rise up, O Lord, in the command which you have ordained, and the assembly of the peoples shall surround you." Second, the fruit was increased from the manner of believing; hence they say to the woman, "Now we believe, not because of your speech." But it is to be noted that three things are necessary for the perfection of faith, which are here set down in order. First, that it be right; second, that it be prompt; third, that it be certain. Faith is indeed right, when obedience is given to the truth not on account of something else, but to it on account of itself; and with regard to this he says that they said to the woman that "now we believe the truth, not because of your speech, but because of the truth itself." Now three things induce us to the faith of Christ. First indeed, natural reason. Romans 1:20: "The invisible things of God are clearly seen, being understood by the things that are made, from the creation of the world." Second, the testimonies of the law and the prophets. Romans 3:21: "But now the justice of God, without the law, is made manifest, being witnessed by the law and the prophets." Third, the preaching of the apostles and of others. Romans 10:14: "How shall they believe, without a preacher?" But when a man, led by the hand through this, believes, then he can say that he believes on account of none of these: neither on account of natural reason, nor on account of the testimonies of the law, nor on account of the preaching of others, but on account of the truth itself alone; Genesis 15:6: "Abraham believed God, and it was reputed to him unto justice." Faith is indeed prompt, if it believes quickly: and this was the case in these men, since at the mere hearing they had been converted to God; hence they say, "For we ourselves have heard, and yet we believe him, and we know that this is truly the savior of the world," without our having seen miracles, as the Jews saw. And although to believe men quickly pertains to levity, according to that saying of Ecclesiasticus 19:4: "He who believes easily is light of heart," nevertheless to believe God quickly is rather praise, according to that saying of Psalm 17:45: "At the hearing of the ear he has obeyed me." Faith must be certain, because he who doubts in faith is unfaithful; James 1:6: "But let him ask in faith, nothing wavering." And therefore the faith of these men was certain, hence they say, "and we know." For sometimes believing itself is called knowing, as is evident here: because knowledge and faith agree in certitude. For just as knowledge is certain, so also is faith: indeed much more so, because the certitude of knowledge rests upon human reason, which can be deceived, but the certitude of faith rests upon divine reason, which cannot be contradicted. They differ, however, in mode: because faith has its certitude from a light divinely infused, but knowledge from the natural light. For just as the certitude of knowledge is had through first principles known naturally, so also the principles of faith are known from a light divinely infused; Ephesians 2:8: "By grace you are saved through faith; and this not of yourselves, for it is the gift of God." Third, the fruit was increased from the truth of what was believed; and therefore he says, "that this is truly the savior of the world": where they confess Christ as a singular, true, and universal savior. Singular indeed, since, distinguishing him from others, they say "this is he" — namely, he who came to save in a singular way. Isaiah 45:15: "Truly you are a hidden God, the God of Israel, the savior." Acts 4:12: "There is no other name under heaven given to men, whereby we must be saved." True, moreover, when he says "truly": for since, according to Dionysius, salvation is liberation from evils and preservation in goods, there is a twofold salvation: one true, another not true. True salvation indeed, when we are freed from true evils, and preserved in true goods. In the Old Testament, although certain saviors were sent, they did not, however, truly save: because they freed from temporal evils, which are not true evils, nor true goods, since they are transitory. But Christ is truly the savior, who frees from true evils, namely sins; Matthew 1:21: "For he shall save his people from their sins." And he preserves in true goods, that is, spiritual ones. Universal, moreover, because he is not a particular savior, namely of the Jews only, but of the world. Above, chapter 3:17: "For God did not send his Son to judge the world, but that the world might be saved through him."”

Reformation

c. 1500 – 1650
1637
A.D.
1567–1637
“And said to the woman, &c. Saviour of the world, understand Messiah, as the Syriac Version adds, who was sent by God for the salvation not of Israel only, as the Jews pretended, but of all the nations of the whole world. Of the world I say, lost by sin. Deservedly does S. Chrysostom in this place admire the, as it were, sudden faith of the Samaritans, when the Jews were so dilatory and hard to believe in Christ”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“And said unto the woman,.... Who, it appears, kept hearing Christ, attending on him, and conversing with him; for having tasted of his grace, she could not leave him: now we believe, not because of thy saying; not on account of that only: it should seem that these were the same persons that believed upon her word before they went out of the city; and who, when come to Christ, invited him into it; and now, having heard his excellent discourses, were confirmed in the faith of him: for we have heard him ourselves; not only externally with their bodily ears, but internally, having ears given them to hear, so as to understand what he said; to mix it with faith, and receive it in love; to feel the power of it in their hearts, and taste the sweetness of it, and be nourished by it; and so as to distinguish his voice from another's, as Christ's true sheep are capable of. And know that this is indeed the Christ; the true Messiah, and not a false one; the Messiah spoken of by Moses, whose books the Samaritans received, as the seed of the woman, the Shiloh, and prophet, like to Moses; the Christ of God, who is anointed to be prophet, priest, and King. The Vulgate Latin and Ethiopic versions leave out the word "Christ", and only read what follows, the Saviour of the world: they knew him to be the Saviour, he who was spoken of as such; for his work to bruise the serpent's head implies it, and his name Shiloh imports as much: and besides, he is called by Jacob God's salvation, Gen 49:18. God appointed him as a Saviour; he sent him, and he came as such, and is become the author of salvation; and his name is called Jesus, on this account: and a great Saviour he is; both able, and willing; and he is suitable to the case of sinners; and is a complete, and an only one: and these Samaritans knew him to be "the Saviour of the world"; not of every individual person in it, for all are not saved by him; nor of the Jewish world, for many of them died in their sins; but of the Gentiles, in distinction from the Jews; see Joh 3:16; even of all God's elect, whether among Jews or Gentiles; of all that believe in him, of whatsoever nation, and in whatsoever state and condition: so that their knowledge of him, and faith in him, were beyond that of the Jews, who looked upon the Messiah only as a Saviour of their nation; and that the Gentiles would have no manner of benefit and advantage by him: though the Jews (b) do call the angel in Exo 23:20 , "the Saviour", or "Redeemer of" the world. And this the Samaritans might know from the writings of Moses, as from Gen 22:18 their present knowledge of Christ was not a mere notional, speculative, and general one, but was special, spiritual, and saving, which they had from the spirit of wisdom and revelation in the knowledge of Christ; they approved of him as their Saviour; they trusted in him as such; they had an experimental acquaintance with him, and practically owned him; and which they attained to by hearing him. (b) Zohar in Gen. fol. 124. 4.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“We have heard him ourselves - On seeing and hearing our Lord, the faith of those who had already believed on the woman's testimony was abundantly confirmed; and, besides those, may others believed who had not heard the woman speak. This is indeed the Christ - The promised Messiah. The Savior of the world - Not of the Jews only, but of the Samaritans, and of the whole Gentile world.”
Source
1849
A.D.
1774–1849
“This is indeed the Saviour of the world. These Samaritans then believed that Jesus was the true Messias, sent to redeem the world. (Witham)”
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.