He is about to do so that they might be prepared for it. The disciples needed the self-examination that comes through prayer and supplication, that they might be ready for the tremendous event which was about to take place, the coming to earth of God the Holy Spirit to dwell in believers and empower them to witness for Him.[12] Luke makes special note of the people present. During His earthly ministry, Jesus had chosen twelve men to receive concentrated spiritual instruction and leadership training.