2 Samuel 21:8-9

8So the king took the two sons of Rizpah the daughter of Aiah, whom she bore to Saul, Armoni and Mephibosheth, and the five sons of Merab the daughter of Saul, whom she had borne to Adriel the son of Barzillai the Meholathite.

9He handed them over to the Gibeonites, and they hanged them on the hill before the Lord, and the seven died together. They were put to death in the first days of the grain harvest, the beginning of the barley harvest [in the spring].