2 Samuel 17:18-22

Nevertheless a lad saw them, and told Absalom: but they went both of them away quickly, and came to a man’s house in Bahurim, which had a well in his court; whither they went down.

And the woman took and spread a covering over the well’s mouth, and spread ground corn thereon; and the thing was not known.

And when Absalom’s servants came to the woman to the house, they said, Where is Ahimaaz and Jonathan? And the woman said unto them, They be gone over the brook of water. And when they had sought and could not find them, they returned to Jerusalem.

And it came to pass, after they were departed, that they came up out of the well, and went and told king David, and said unto David, Arise, and pass quickly over the water: for thus hath Ahithophel counselled against you.

Then David arose, and all the people that were with him, and they passed over Jordan: by the morning light there lacked not one of them that was not gone over Jordan.