John the Apostle
Revelation 2:5ESV·traditional attribution

Remember therefore from where you have fallen; repent, and do the works you did at first. If not, I will come to you and remove your lampstand from its place, unless you repent.

Matthew Henry Presbyterian @wholebiblehenry

We have here, I. The inscription, where observe, 1. To whom the first of these epistles is directed: To the church of Ephesus, a famous church planted by the apostle Paul (Acts 19), and afterwards watered and governed by John, who had his residence very much there.

Commenting on Revelation 2:1-7

John Gill Reformed Baptist @doctorgill

Remember therefore from whence thou art fallen,.... Believers cannot totally and finally fall away from the grace which they have received; but they may fall into sin, and from a degree of grace, and the exercise of it, as these first and pure churches did, from some degree of their love to God, and Christ, and one another; and therefore are called upon to remember...

Albert Barnes Presbyterian @notesbybarnes

Verse 5. Remember therefore from whence thou art fallen. The eminence which you once occupied. Call to remembrance the state in which you once were. The duty here enjoined is, when religion has declined in our hearts, or in the church, to call to distinct recollection the former state--the ardour, the zeal, the warmth of love which once characterized us.