Men and brethren, this scripture must needs have been fulfilled, which the Holy Spirit by the mouth of David spoke before concerning Judas, who was guide to them that took Jesus.
All Commentaries on Acts 1:16 Go To Acts 1
Thomas Aquinas
AD 1274
the scripture had to be fulfilled: Not that scripture forced the event, but it did mention an event that would happen: This scripture says: He who ate my bread has lifted his heel against me.(Psalm 41:9)
who was the leader of those who apprehended Jesus: Judas had agreed with the chief priests to betray Christ, he looked for an opportunity to deliver him without disturbing the people. And because some of the crowd might resist, he took a band of soldiers, not from the Jews, but from the governor. In this way, no one would dare to resist because they would see the marks of legitimate authority. Further, some Jews might resist out of zeal for the law, especially because Christ was being taken by Gentiles. For this reason Judas took some servants or officers from the chief priests and the Pharisees. (John 18:3)