Proverbs 5:1

My son, attend unto my wisdom, and bow thine ear to my prudence, that thou mayest guard thy thoughts. For, indeed, nothing is more fugitive than the heart, which deserts us as often as it slips away through bad thoughts. For hence the Psalmist says, My heart hath failed me. Hence, when he returns to himself, he says, Thy servant hath found his heart to pray to Thee. When, therefore, thought is kept under guard, the heart which was wont to fly away is found.

My son, attend to my wisdom, etc. Until now he had generally rebuked the listener; hence under the guise of the harlot, he prohibits from the wickedness of heretics.