15 Then Hushai told the priests Zadok and Abiathar, "Ahithophel advised Absalom and the elders of Israel thus and thus, and I advised them thus and thus. 16 Now send this message as quickly as possible to David: 'Don't spend the night on this side of the river; cross immediately or the king and everyone with him will be swallowed up alive.'" 17 Jonathan and Ahimaaz were waiting around at En Rogel. A servant girl would come and give them messages and then they would go and tell King David, for it wasn't safe to be seen coming into the city.
Matthew Henry's Commentary on 2 Samuel 17:15-17
Commentary on 2 Samuel 17:1-21
(Read 2 Samuel 17:1-21)
Here was a wonderful effect of Divine Providence blinding Absalom's mind and influencing his heart, that he could not rest in Ahithophel's counsel, and that he should desire Hushai's advice. But there is no contending with that God who can arm a man against himself, and destroy him by his own mistakes and passions. Ahithophel's former counsel was followed, for God intended to correct David; but his latter counsel was not followed, for God meant not to destroy him. He can overrule all counsels. Whatever wisdom or help any man employs or affords, the success is from God alone, who will not let his people perish.