As Absalom and Israel rebelled against David, he put in a place a spy, who would advise Absalom to take certain action against David, and then the spy, Hushai, would inform David,

Then Hushai said to Zadok and Abiathar the priests, “Thus and so Ahithophel advised Absalom and the elders of Israel, and thus and so I have advised. Now therefore, send quickly and tell David, saying, ‘Do not spend this night in the plains of the wilderness, but speedily cross over, lest the king and all the people who are with him be swallowed up’” (2 Samuel 17:15–16).

Hushai risked his life for doing this, because if Absalom had found out, Absalom would have killed him immediately, and Hushai knew it.

Nevertheless, he knew who was in the right, and he knew that God was with David, and not with Absalom. Therefore, Hushai never relinquished his loyalty to David.