The interpretation timeline
Revelation 3:21 Douay-Rheims

To him that shall overcome, I will give to sit with me in my throne: as I also have overcome, and am set down with my Father in his throne.

A.D. 220 – 1871 8 witnesses 10 excerpts

Patristic

before A.D. 750
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“For avoiding it, remedies cannot be lacking; since, even if they be lacking, there remains that one by which you will be made a happier magistrate, not in the earth, but in the heavens.”
“"He sitteth at the Father's right hand " -not the Father at His own.”
235
A.D.
Hippolytus of Rome Patristic
c. A.D. 170–235
“And thou shalt receive the kingdom of heaven, thou who, whilst thou didst sojourn in this life, didst know the Celestial King. And thou shalt be a companion of the Deity, and a co-heir with Christ, no longer enslaved by lusts or passions, and never again wasted by disease. For thou hast become God: for whatever sufferings thou didst undergo while being a man, these He gave to thee, because thou wast of mortal mould, but whatever it is consistent with God to impart, these God has promised to bestow upon thee, because thou hast been deified, and begotten unto immortality. This constitutes the import of the proverb, "Know thyself; "i.e., discover God within thyself, for He has formed thee after His own image. For with the knowledge of self is conjoined the being an object of God's knowledge, for thou art called by the Deity Himself.”
Source
“But give me now your best attention, I pray you, for I wish to go back to the fountain of life, and to view the fountain that gushes with healing. The Father of immortality sent the immortal Son and Word into the world, who came to man in order to wash him with water and the Spirit; and He, begetting us again to incorruption of soul and body, breathed into us the breath (spirit) of life, and endued us with an incorruptible panoply. If, therefore, man has become immortal, he will also be God. And if he is made God by water and the Holy Spirit after the regeneration of the layer he is found to be also joint-heir with Christ after the resurrection from the dead. Wherefore I preach to this effect: Come, all ye kindreds of the nations, to the immortality of the baptism. I bring good tidings of life to you who tarry in the darkness of ignorance. Come into liberty from slavery, into a kingdom from tyranny, into incorruption from corruption. And how, saith one, shall we come? How? By water and the Holy Ghost. This is the water in conjunction with the Spirit, by which paradise is watered, by which the earth is enriched, by which plants grow, by which animals multiply, and (to sum up the whole in a single word) by which man is begotten again and endued with life, in which also Christ was baptized, and in which the Spirit descended in the form of a dove.”
Source
258
A.D.
Cyprian Patristic
c. A.D. 200–258
“For to this battle our Lord, as with the trumpet of His Gospel, stimulates us when He says, "He that loveth father or mother more than me is not worthy of me: and he that loveth his own soul more than me is not worthy of me. And he that taketh not his cross, and followeth after me, is not worthy of me." And again, "Blessed are they which are persecuted for righteousness' sake: for theirs is the kingdom of heaven. Blessed shall ye be, when men shall persecute you, and hate you. Rejoice, and be exceeding glad: for so did their fathers persecute the prophets which were before you." And again," Because ye shall stand before kings and powers, and the brother shall deliver up the brother to death, and the father the son, and he that endureth to the end shall be saved; " and "To him that overcometh will I give to sit on my throne, even as I also overcame and am set down on the throne of my Father." Moreover the apostle: "Who shall separate us from the love of Christ? shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword? (As it is written, For thy sake are we killed all the day long; we are accounted as sheep for the slaughter.) Nay, in all these things we are more than conquerors for Him who hath loved us."”
Source
303
A.D.
c. A.D. 250–303
“And because, if in these ways men return out of great destruction to great repentance, they are not only useful to themselves, but they are able also to be of advantage to many, He promised them no small reward,-to sit, namely, on the throne of judgment.”

Post-Reformation

c. 1650 – 1900
1832
A.D.
Adam Clarke Methodist
1762–1832
“To sit with me in my throne - In every case it is to him that overcometh, to the conqueror, that the final promise is made. He that conquers not is not crowned, therefore every promise is here made to him that is faithful unto death. Here is a most remarkable expression: Jesus has conquered, and is set down with the Father upon the Father's throne; he who conquers through Christ sits down with Christ upon his throne: but Christ's throne and the throne of the Father is the same; and it is on this same throne that those who are faithful unto death are finally to sit! How astonishing is this state of exaltation! The dignity and grandeur of it who can conceive? This is the worst of the seven Churches, and yet the most eminent of all the promises are made to it, showing that the worst may repent, finally conquer, and attain even to the highest state of glory.”
Source
1863
A.D.
1796–1863
“This was to give the sacred seer an insight into the glory of Christ reigning with the Father.”
1871
A.D.
1871
“sit with me in my throne-- (Rev 2:26-27; Rev 20:6; Mat 19:28; Mat 20:23; Joh 17:22, Joh 17:24; Ti2 2:12). The same whom Christ had just before threatened to spue out of His mouth, is now offered a seat with Him on His throne! "The highest place is within reach of the lowest; the faintest spark of grace may be fanned into the mightiest flame of love" [TRENCH]. even as I also--Two thrones are here mentioned: (1) His Father's, upon which He now sits, and has sat since His ascension, after His victory over death, sin, the world; upon this none can sit save God, and the God-man Christ Jesus, for it is the incommunicable prerogative of God alone; (2) the throne which shall be peculiarly His as the once humbled and then glorified Son of man, to be set up over the whole earth (heretofore usurped by Satan) at His coming again; in this the victorious saints shall share (Co1 6:2). The transfigured elect Church shall with Christ judge and reign over the nations in the flesh, and Israel the foremost of them; ministering blessings to them as angels were the Lord's mediators of blessing and administrators of His government in setting up His throne in Israel at Sinai. This privilege of our high calling belongs exclusively to the present time while Satan reigns, when alone there is scope for conflict and for victory (Ti2 2:11-12). When Satan shall be bound (Rev 20:4), there shall be no longer scope for it, for all on earth shall know the Lord from the least to the greatest. This, the grandest and crowning promise, is placed at the end of all the seven addresses, to gather all in one. It also forms the link to the next part of the book, where the Lamb is introduced seated on His Father's throne (Rev 4:2-3; Rev 5:5-6). The Eastern throne is broad, admitting others besides him who, as chief, occupies the center. TRENCH notices; The order of the promises in the seven epistles corresponds to that of the unfolding of the kingdom of God its first beginnings on earth to its consummation in heaven. To the faithful at Ephesus: (1) The tree of life in the Paradise of God is promised (Rev 2:7), answering to Gen 2:9. (2) Sin entered the world and death by sin; but to the faithful at Smyrna it is promised, they shall not be hurt by the second death (Rev 2:11). (3) The promise of the hidden manna (Rev 2:17) to Pergamos brings us to the Mosaic period, the Church in the wilderness. (4) That to Thyatira, namely, triumph over the nations (Rev 2:26-27), forms the consummation of the kingdom in prophetic type, the period of David and Solomon characterized by this power of the nations. Here there is a division, the seven falling into two groups, four and three, as often, for example, the Lord's Prayer, three and four. The scenery of the last three passes from earth to heaven, the Church contemplated as triumphant, with its steps from glory to glory. (5) Christ promises to the believer of Sardis not to blot his name out of the book of life but to confess him before His Father and the angels at the judgment-day, and clothe him with a glorified body of dazzling whiteness (Rev 3:4-5). (6) To the faithful at Philadelphia Christ promises they shall be citizens of the new Jerusalem, fixed as immovable pillars there, where city and temple are one (Rev 3:12); here not only individual salvation is promised to the believer, as in the case of Sardis, but also privileges in the blessed communion of the Church triumphant. (7) Lastly, to the faithful of Laodicea is given the crowning promise, not only the two former blessings, but a seat with Christ on His throne, even as He has sat with His Father on His Father's throne (Rev 3:21). Next: Revelation Chapter 4”
Source

Undated

date unknown
date
unknown
Glossa Ordinaria Medieval
“To sit with me in my throne. To judge in those in whom I sit and judge. These things of prelates, and, through prelates, of subjects. As I also have overcome and have sat with my Father in his throne. He speaks thus, because the victory and the session of Christ is the cause of the victory and the session of Christians.”
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.