12Then returned they unto Jerusalem from the mount called Olivet, which is from Jerusalem a sabbath day’s journey.
13And when they were come in, they went up into an upper room, where abode both Peter, and James, and John, and Andrew, Philip, and Thomas, Bartholomew, and Matthew, James the son of Alphaeus, and Simon Zelotes, and Judas the son of James.
14These all continued with one accord in prayer and supplication, with the women, and Mary the mother of Jesus, and with His brethren.
returned unto Jerusalem (v.12) — Luke 24:52
The name [the mount called Olivet — v.12] denotes the range of hills which faces Jerusalem on the east and, lying round about from north-east to south-east, is separated from the city by the valley of Jehoshaphat or Kidron. It’s whole length, from north to south, is about two miles, and its average height above the level of the sea is about 2,600 feet, though it has several summits of a slightly higher altitude. It rises about 400 feet above the bed of the Kidron, and towers 200 feet above the highest part of Jerusalem. During the siege of Jerusalem by the Romans, it was denuded of the olive trees which once luxuriated there.
The traditional distance allowed for a sabbath day’s journey was 2,000 cubits [a cubit was about 18 inches] or about six furlongs [about 3,000 feet]. The Rabbis arrived at this measurement by a fanciful connection and interpretation of Exodus 16:29; 21:13; and Numbers 35:5, 26-27; and by giving an allegorical meaning to the word “place.” Josephus, the Jewish historian, tells us that the mount of Olives is five or six furlongs distant from Jerusalem, so that the statement of this verse is seen to be correct. — The Acts of the Apostles, by Thomas Walker, p. 13.
Simon Zelotes (v,13) =of Cananaean
Judas the son of James (v.13) — called Thaddeus in Matthew 10:2-4 and Mark 3:16-19.
continued (v.14) = continued persisting
one accord (v.14) = one heart and mind — perfect unity
in prayer (v.14) = lit. “in the prayer” — for the Holy Spirit. The Spirit came 10 days later, but as a result of the promise, not because of their prayers.
women (v.14) — probably those, or at least some of those, mentioned throughout the Gospels — Mary Magdalene, Salome, Mary of Clopas, Susanna, Joanna, Mary and Martha of Bethany
Mary the mother of Jesus (v.14) — her last mention in Scripture
brethren (v.14) — Jesus’ brothers did not believe in Him as Savior during His ministry (John 7:5) and perhaps not until after His resurrection (1 Corinthians 15:7). They were James, Joseph, Simon, Judas (Matthew 13:55; Mark 6:3).