Peter gives a sermon to the crowd gathered in Jerusalem on the day of Pentecost explaining the events that had just occurred. He establishes the basis of his faith by noting that: 1) the disciples were not drunk as it was only 9am, instead they were experiencing the outpouring of God's spirit as prophesied. 2) Jesus had been approved by God through his works but was crucified and raised according to God's plan. 3) The psalms and David had prophesied that Jesus would not be kept in the grave. Peter calls the crowd to witness these events and recognizes Jesus as the Lord and Messiah foretold in scripture.