A.T. Robertson Commentary Revelation 3:19

"As many as I love, I reprove and chasten: be zealous therefore, and repent." — Revelation 3:19 (ASV)

Free rendering of Pr 3:12 , but with ους εαν (indefinite relative plural) for ον (definite relative singular), with φιλω instead of αγαπα and with the first person παιδευω for παιδευε (the Lord chastens, from παις, child, training a child) and with ελεγχω (reprove) added.

Be zealous (ζηλευε). Present active imperative of ζηλευω, in good sense (from ζηλοσ, ζεω, to boil), in opposition to their lukewarmness, here only in N.T. (elsewhere ζηλοω), "keep on being zealous."

Repent (μετανοησον). Ingressive first aorist active imperative of μετανοεω.