2 Samuel 17:19
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 the woman took and spread a covering over the well’s mouth, and spread ground corn thereon; and the thing was not known.
The covering spread over the well's mouth hid the messengers and let Hushai's warning get through to David. Hushai did not wait, because he could not be sure the changeable king would follow his counsel, and he sent word at once for David to escape beyond the Jordan without delay. He sent it through the priests to be carried forward by their sons. The message set out what Ahithophel had counseled Absalom and the elders of Israel in contrast with what Hushai himself had counseled. It directed David not to lodge that night in the plains of the wilderness but to pass speedily over, lest the king be swallowed up and all the people with him.
The young bearers of that message were suspected and pursued, so their mission was perilous, yet they succeeded in performing it. David had spent the first day of flight in toil and grief and was worn out when the word reached him. The word told him he must cross the Jordan that night because his own son was seeking his life.