What did Peter and John pray for the Samaritans when they arrived?
When Peter and John came down to Samaria, they prayed for the Samaritan believers that they might receive the Holy Spirit, because the Spirit had not yet fallen on them; afterward they laid hands on them and they received the Holy Spirit.
Les explains that the apostles at Jerusalem heard Samaria had received the Word of God, so they sent Peter and John down to Samaria. He notes James was probably already dead, which is why the pair was Peter and John rather than Peter, James, and John. When they arrived, they prayed for the Samaritan believers that they might receive the Holy Spirit. As yet the Spirit had fallen on none of them; they had only been baptized in the name of the Lord Jesus. Les says God had His reasons for this. Then Peter and John laid their hands on the Samaritan believers, and they received the Holy Spirit—something Les presents as amazing.
Who, when they were come down, prayed for them, that they might receive the Holy Ghost: