2 Sam 16:21

16:21 Go in to your father’s concubines. To remove any thought among Absalom’s followers of a reconciliation with David, Ahithophel counsels Absalom to lie with David’s concubines who had been left behind (15:16). This would make clear Absalom’s desire for the throne (3:7 note; 12:8 note; 1 Kin. 2:22). Whatever the motivation, such behavior was detestable to God (Lev. 18).