The Septuagint adds, what is a good explanation, “but he did not vex the spirit of Amnon his son, because he loved him, because he was his first-born.” This want of justice in David’s conduct, and favoritism to Amnon, probably rankled in Absalom’s heart, and was the first seed of his after rebellion.
Related Commentaries of 2 Samuel 13:21
2 Samuel 13:21
21 But when king David heard of all these things, he was very wroth.