Luke
Acts 12:12ESV·traditional attribution

When he realized this, he went to the house of Mary, the mother of John whose other name was Mark, where many were gathered together and were praying.

John Calvin Reformed @genevareformer

12. Into the house of Mary It appeareth that she was a matron of rare godliness, whose house was, as it were, a certain temple of God, where the brethren did use to meet together. And Luke saith that there were many assembled there, because, seeing they could not all meet together in one place without fear of some tumult, they came together in diverse...

Matthew Henry Presbyterian @wholebiblehenry

We have here an account of Peter's deliverance out of prison, by which the design of Herod against him was defeated, and his life preserved for further service, and a stop given to this bloody torrent. Now, I. One thing that magnified his deliverance was that it was a signal answer to prayer (Act 12:5): Peter was kept in prison with a great deal of...

Commenting on Acts 12:5-19

John Gill Reformed Baptist @doctorgill

And when he had considered the thing,.... The whole of the salvation wrought for him; or rather, where he should go, to what house he should betake himself; ere he was aware, he came to the house of Mary the mother of John, whose surname was Mark. This good woman seems to be a widow, no mention being made of her husband, and was sister to Barnabas, Col 4:10.