Hushai told Zadok and Abiathar, the priests, "Ahithophel has advised Absalom and the elders of Israel to do such and such, but I have advised them to do so and so.
Now send a message immediately and tell David, 'Do not spend the night at the fords in the desert;1 cross over without fail, or the king and all the people with him will be swallowed up.2' "
References for 2 Samuel 17:16
Jonathan3 and Ahimaaz were staying at En Rogel.4 A servant girl was to go and inform them, and they were to go and tell King David, for they could not risk being seen entering the city.
References for 2 Samuel 17:17