Verse 14 and 15 are a window into the internal workings of disciples.
Verse 14 All these with one accord were devoting themselves to prayer, together with the women and Mary the mother of Jesus, and his brothers.
Verse 15 In those days Peter stood up among the brothers (the company of persons was in all about 120) and said,
All these with one accord: They were unified, they were together aiming in one direction, they had priorities higher than themselves. This is instructive for Christians. Divisions hurt the very heart of the church.
were devoting themselves to prayer: Alongside unity, a devotion to prayer is much needed in the church. In the modern church much is said about prayer, but little praying is actually done. It’s easier talk about it than to do it. We’ll pray for someone or for something, but soon forget it. A devotion to prayer is old school. It is a life priority. It is a morning, afternoon, and evening commitment. It is a love. The desire to talk with God reveals who we are.
together with the women: Men will be the central characters in Acts, as they were in the gospels, and as they were in the Old Testament. Nevertheless, the body of Christ is at its best when it has a high spiritual view of women. The church needs strong, mature, Bible-immersed, seriously-praying women.
Mary the mother of Jesus: This is the last time Mary is mentioned in the Bible.
his brothers: By all indications, Jesus’ brothers did not believe in Him in the four gospels. But something changed in Acts. We know Jesus appeared to His brother James after his resurrection (see 1 Corinthians 15:7). And James will show up several more times in the book of Acts (see Acts 12:17, 15:13, & 21:18).
Peter: Time and again God uses people we would not expect Him to use. Peter the mouthy one, the one who denied Jesus, becomes the spiritual leader of the disciples. Never underestimate God using anyone. It is, though, good to remind ourselves of the confrontation Jesus and Peter had in John 21:15-19. The issue is two-fold. The depth and breadth of Peter’s love. Jesus pressed Peter. He needed to be confronted about this. He had been mouthy, but he had not loved Jesus. Second, Jesus’ insistence that Peter “Feed my lambs. Tend my lambs. Feed my sheep. Follow me.” Peter was given explicit marching orders. He had an all-consuming job to do.
brothers: This is the first time the term is used in Acts, and it’ll show up over fifty times. This is a good term, and a needed term. But it is a difficult term. We like the term until we don’t. Someone is brother to us until they have crossed one line too many. One of the truest tests of our spiritual maturity and love is how we talk about a “brother” behind their back who is under our skin, or hurt us, or we don’t trust.
These are two helpful and insightful verses. There is much to think about and much to learn.
Another helpful and short and GOOD video
The Men's Bible Reading Idea 