C. F. Keil and Franz Delitzsch on Proverbs 28:9

Pro 28:9 9 He who turneth away his ear not to hear of the law,    Even his prayer is an abomination.

Cf. Pro 15:8 and the argument 1Sa 15:22. Not only the evil which such an one does, but also the apparent good is an abomination, an abomination to God, and eo ipso also in itself: morally hollow and corrupt; for it is not truth and sincerity, for the whole soul, the whole will of the suppliant, is not present: he is not that for which he gives himself out in his prayer, and does not earnestly seek that which he presents and expresses a wish for in prayer.