1 Samuel 7:15

And Samuel judged Israel all the days of his life. Not only before Saul was made king, but afterwards; for though he had not the exercise of the supreme government of the nation, yet he might act as a judge under Saul, and hear and try causes brought before him, and execute justice and judgment; and as a prophet he taught and instructed the people, and reformed abuses among them; and besides, he held and exercised his extraordinary office, to which he was raised up of God, and even took upon him to reprove Saul himself, and to kill Agag. The Jews say q he judged Israel thirteen years only, eleven by himself, and two with Saul; but his government must be much larger, his with Saul is reckoned forty years, Acts 13:21.

q Seder Olam Rabba, c. 13. p. 35. Midrash Tillim apud Abarbinel in loc. Kimchi in loc.