2 Corinthians 12:9

said--literally, "He hath said," implying that His answer is enough [ALFORD]. is sufficient--The trial must endure, but the grace shall also endure and never fail thee [ALFORD], (Deu 33:25). The Lord puts the words into Paul's mouth, that following them up he might say, "O Lord, Thy grace is sufficient for me" [BENGEL]. my strength--Greek, "power." is made perfect--has its most perfect manifestation. in weakness--Do not ask for sensible strength, FOR My power is perfected in man's "strengthlessness" (so the Greek). The "for" implies, thy "strengthlessness" (the same Greek as is translated "weakness"; and in Co2 12:10, "infirmities") is the very element in which My "power" (which moves coincident with "My grace") exhibits itself more perfectly. So that Paul instead of desiring the infirmity to "depart," "rather" henceforth "glories in infirmities, that the power of Christ may rest (Greek, 'tabernacle upon,' cover my infirmity all over as with a tabernacle; compare Greek, Joh 1:12) upon" him. This effect of Christ's assurance on him appears, Co2 4:7; Co1 2:3-4; compare Pe1 4:14. The "My" is omitted in some of the oldest manuscripts; the sense is the same, "power" (referring to God's power) standing absolutely, in contrast to "weakness" (put absolutely, for man's weakness). Paul often repeats the word "weakness" or "infirmity" (the eleventh, twelfth, and thirteenth chapters) as being Christ's own word.

— Jamieson-Fausset-Brown Commentary (public domain)