John Gill Bible Commentary

And the king said to Absalom, nay, my son, let us not all now go,.... He did not object to the invitation entirely, he was willing some of the family should go, but not all; it seems probable that he particularly excepted himself and his eldest son, the heir to his crown, for the reason following: lest we be chargeable unto thee; one or two persons more, supposing them to be private persons, would have added but little to the expense, if any; but as David was a king, he must have come with the retinue of a king, with a large number of servants and guards, and must be entertained as such; and Amnon, his eldest son, and heir apparent to the crown, must make a figure suitable to his quality, which would have considerably raised the expense; and perhaps Absalom's estate he had to live upon might be but small, which David knew, and therefore chose not to be burdensome to him: and he pressed him; urged him to go; not that he expected he would, or really desired he should, but this he did to hide his intention, that he might have no suspicion of his design against Amnon; or otherwise he might think he would not have been so pressing upon him to go with him: howbeit he would not go, but blessed him; thanked him for the invitation he gave him, and wished him much happiness and pleasure at his entertainment with his friends.