But Amnon had a friend,.... Though in the issue his friendship proved his ruin:
whose name [was] Jonadab, the son of Shimeah, David's brother; so that they were own cousins, the same with Shammah, 1 Samuel 16:9;
and Jonadab [was] a very subtle man; a very penetrating man into the dispositions of men, and could judge by their countenances what they were, and the affections of their minds, and had a talent in forming schemes; he was wise to do evil and was wickedly cunning.