A.T. Robertson Commentary Galatians 1:11

"For I make known to you, brethren, as touching the gospel which was preached by me, that it is not after man." — Galatians 1:11 (ASV)

Which was preached (το ευαγγελισθεν). Play on the word ευαγγελιον by first aorist passive participle of ευαγγελιζω, "the gospel which was gospelized by me."

It is not after man (ουκ εστιν κατα ανθρωπον). Not after a human standard and so he does not try to conform to the human ideal. Paul alone (1 Corinthians 3:3; 1 Corinthians 9:8; 1 Corinthians 15:32; Romans 3:15) in the N.T. uses this old and common idiom.