V.1-11 Peter and John had not yet learned that God was drawing them away from the temple. Full truth had not yet been revealed. The Jews were used to praying three times a day (1) at the 3rd hour, 9 a.m., (Acts 2:15); (2) at the 6th hour, noon, (Acts 10:9); (3) here the 9th hour, 3 p.m.
V.12-26 Peter makes one more appeal to the Jewish nation. He charges them with having killed the Prince of life, but at the same time shows that this fulfilled the Scriptures.
V.19-21 Even at this time if they would repent, Christ would come back, their sins as a nation would be forgiven, and the kingdom would be set up, according to all the Old Testament prophets. This offer was made even after the church was formed, showing how merciful God is.