John Gill Commentary 2 Samuel 15:28

"See, I will tarry at the fords of the wilderness, until there come word from you to certify me." — 2 Samuel 15:28 (ASV)

See, I will tarry in the plain of the wilderness
Towards the way of which David and the people went when they came over Kidron, (2 Samuel 15:23);

until there come word from you to certify me;
of the truth of the conspiracy, of the number of the conspirators, and who they are, what progress they have made, whether come to Jerusalem, and how they behave there, if come; or of anything relative hereunto he could get intelligence of.