John Gill Commentary 2 Samuel 18:4

"And the king said unto them, What seemeth you best I will do. And the king stood by the gate-side, and all the people went out by hundreds and by thousands." — 2 Samuel 18:4 (ASV)

And the king said to them, what seems best to you I will do ,
&c.] Which was an instance of great condescension in him; and it was his wisdom and prudence to yield to them at such a time as this, and especially as their sentiments were founded on affection and loyalty to him:

and the king stood by the side of the gate ;
of the city of Mahanaim:

and all the people came out by hundreds, and by thousands ;
and passed by him, to whom no doubt he gave his blessing and best wishes; and, as Abarbinel thinks, now it was he composed and said the twentieth psalm, "The Lord hear thee in the day of trouble" (Psalms 20:1–9) .