The Healing of the Lame Man (3:1-11).
‘Now Peter and John were going up into the temple at the hour of prayer, being the ninth hour.'
Peter and John being together (compare Acts 1:13) seems to suggest that the Apostles continued to go around in pairs as they had done while preaching during the ministry of Jesus (Mark 6:7; Luke 10:1), and as Paul would do in the future. This would also have provided another reason why they felt it necessary to make up the twelve. But while the Apostles were all on a par and were depicted as acting as a whole (Acts 2:14; Acts 2:37; Acts 2:42-43; Acts 4:35; Acts 5:2; Acts 5:12-13; Acts 5:29; Acts 6:2; Acts 6:6; Acts 8:14; Acts 15:6), Peter tended to be the public spokesman (Acts 2:14; Acts 5:3; Acts 5:29), and Peter and John appear to have been given special prominence (compare Acts 8:14; Galatians 2:9), although very much as representatives of the whole body of disciples. They had after all been a part of the favoured trio of Peter, James and John (Mark 5:37; Mark 9:2; Luke 8:51; Luke 9:28).
There were a number of recognised times of public prayer at the Temple. These included the morning prayers around the time of the morning sacrifice (compare the third hour (9:00 am) in Acts 2:15) and the afternoon prayers around the time of the evening sacrifice (the ninth hour - 3:00 pm). These would include formal priestly prayer, and free prayer in the outer courts. Peter and John were going to join with the young church in their afternoon worship (compare Acts 2:46; Luke 24:53).
‘Going up.' The worshippers would ascend the Temple Mount. But it also contains the idea of respect and reverence. They have to ‘go up' to God.