And afterward they desired a king: and God gave unto them Saul the son of Cis, a man of the tribe of Benjamin, by the space of forty years.
Note 6 at Ac 13:21: Saul was the first king of Israel. He started out with great humility (1Sa 10:21-23, 27; and 15:17), but he quickly became lifted up in pride (Pr 16:18) and was rejected by God as being Israel's king (1Sa 15:23-29). The Lord chose David as Saul's replacement.
Note 7 at Ac 13:21: This is the only place in Scripture that the length of Saul's reign is given. The first-century Jewish historian Josephus also ascribed forty years as the length of Saul's reign (The Antiquities of the Jews, Book 6, Chapter 14, Section 9). Just as in Stephen's account of Jewish history (see note 2 at Ac 7:2), this is a very important piece of information that fills a gap in the Old Testament historical account.