And Absalom said to Hushai, Is this thy kindness to thy {i} friend? why wentest thou not with thy friend?

(i) Meaning, David.

Wesley's Notes

16:17 Is this - Doth this action answer that profession of friendship which thou hast hitherto made to him? He speaks thus only to try him. And he saith, thy friend, by way of reflection upon David; as one who was a friend to Hushai, and to strangers but not to his own son, whom, by his severity he provoked to this course; and therefore he doth not vouchsafe to call him his father.

Matthew Henry's Concise Commentary

16:15-23 The wisest counsellors of that age were Ahithophel and Hushai: Absalom thinks himself sure of success, when he has both; on them he relies, and consults not the ark, though he had that with him. But miserable counsellors were they both. Hushai would never counsel him to do wisely. Ahithophel counselled him to do wickedly; and so did as effectually betray him, as he did, who was designedly false to him: for they that advise men to sin, certainly advise them to their hurt. After all, honesty is the best policy, and will be found so in the long run. Ahithophel gave wicked counsel to Absalom; to render himself so hateful to his father, that he would never be reconciled to him; this cursed policy was of the devil. How desperately wicked is the human heart!