John Gill Commentary 2 Samuel 19:27

"And he hath slandered thy servant unto my lord the king; but my lord the king is as an angel of God: do therefore what is good in thine eyes." — 2 Samuel 19:27 (ASV)

And he has slandered your servant unto my lord the king
By suggesting that he stayed at Jerusalem with a view to the kingdom, hoping that the quarrel between David and Absalom would issue in the restoration of it to his father's family; which was a mere calumny, he having had no such thought, nor was there any foundation for it:

but my lord the king [is] an angel of God ;
for understanding and wisdom, to discern the falsehood of such suggestions:

do therefore [what is] good in your eyes ;
condemn him or acquit him; reject him or receive him into favour; he entirely submitted himself to him, to do with him as seemed good in his sight.