Albert Barnes Commentary 2 Samuel 17:16

"Now therefore send quickly, and tell David, saying, Lodge not this night at the fords of the wilderness, but by all means pass over; lest the king be swallowed up, and all the people that are with him." — 2 Samuel 17:16 (ASV)

Hushai, as a wise and prudent man who also knew Absalom’s weak and fickle character, did not rely on the resolution made at his instigation—not to pursue the king—but took immediate measures to warn David of his danger.