John Calvin Commentary Acts 13:20

"and after these things he gave [them] judges until Samuel the prophet." — Acts 13:20 (ASV)

He gave them judges. Under this name, Scripture includes rulers and governors; and this is another testimony to God's infinite goodness toward the Jews, in that He pardoned so many of their backslidings. For it is likely that Paul discussed these matters in greater detail, which Luke briefly summarizes.

And we know what the state of the people was during all that time, since through untamed wantonness they time and again shook off the yoke. They were often punished with most grievous plagues, yet as soon as they were humbled, God delivered them from the tyranny of their enemies.

So He preserved them as a people, amidst many deaths, for four whole ages and a half. And by this it appears how unworthy they were of God's favor, which they so often despised and rejected, unless the constancy of their election had prevailed. For how is it that God is never weary, but keeps His promise with those who are truce-breakers a hundred times, except that, turning His eyes toward His Christ, He has not allowed His covenant, grounded in Him, to decay or perish?