John Gill Commentary 2 Samuel 17:7

"And Hushai said unto Absalom, The counsel that Ahithophel hath given this time is not good." — 2 Samuel 17:7 (ASV)

And Hushai said to Absalom
Having leave to give his opinion freely:

the counsel that Ahithophel has given is not good at this time ;
he owns that Ahithophel was a good counsellor, and that the counsel he gave was for the most part, if not always, good, but what he gave at this time was not so; the wisest of men may sometimes be mistaken. Abarbinel thinks he respects his former counsel, particularly that that was good, advising him to defile his father's bed, (2 Samuel 16:21) ; but this was not, for which he gives the following reasons.