John Gill 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)

Now therefore send quickly and tell David What has been advised to on both sides:

saying, lodge not this night in the plains of the wilderness ; which reached to Jericho; this advice he gave, because he knew not whether his counsel would be abode by, though preferred; Absalom and the elders of Israel might change their minds, and Ahithophel might, by the strength of his oratory, prevail upon them after all to follow his advice; and therefore, to guard against the worst, he judged it most prudential in David to make all the haste he could from that place where he was, and not continue a night longer in it; for, if Ahithophel's counsel should take place, he would be in pursuit of him that very night:

but speedily pass over ; the river Jordan:

lest the king be swallowed up, and all the people that [are] with him : be destroyed by the forces Ahithophel should bring with him, which he would not be able to withstand.