A.T. Robertson Commentary Hebrews 12:17

"For ye know that even when he afterward desired to inherit the blessing, he was rejected; for he found no place for a change of mind [in his father,] though he sought is diligently with tears." — Hebrews 12:17 (ASV)

Ye know (ιστε). Regular form for the second person of οιδα rather than the Koine οιδατε.

He was rejected (απεδοκιμασθη). First aorist passive indicative of αποδοκιμαζω, old verb to disapprove (Matthew 21:42).

Place of repentance (μετανοιας τοπον). Μετανοια is change of mind and purpose, not sorrow though he had tears (μετα δακρυων) afterwards as told in Ge 27:38. He sought it (αυτην, the blessing ευλογιαν) with tears, but in vain. There was no change of mind in Isaac. The choice was irrevocable as Isaac shows (Genesis 27:33). Esau is a tragic example of one who does a wilful sin which allows no second chance (Hebrews 6:6; Hebrews 10:26). The author presses the case of Esau as a warning to the Christians who were tempted to give up Christ.