Albert Barnes Commentary Acts 13:31

"and he was seen for many days of them that came up with him from Galilee to Jerusalem, who are now his witnesses unto the people." — Acts 13:31 (ASV)

And he was seen. See the notes on Matthew 28:20.

Many days. Forty days (Acts 1:3).

Of them which came up. By the apostles particularly. He was seen by others; but they are especially mentioned as having been chosen for this purpose, to bear witness to Him, and as having been particularly qualified for it.