Before Jesus began his work for God, Jesus had left the people. He went away from the towns. He was alone for 40 days (Mark 1:12-13). Jesus always obeyed God his father. So during those days, Jesus prayed. And he prepared for his special work.
Soon, Jesus would begin his most important work for God. Jesus already knew what would happen. There would be many troubles for him, and he would die (Mark 8:31; Isaiah chapter 53). This work would be very difficult. But God had sent Jesus for this reason (John 3:16). Because of it, God would save men and women. And after it, God would cause Jesus to be alive again. And Jesus would receive the most important place in *heaven.
So Jesus had to prepare himself for this difficult work. Again, he left the people. He took three *disciples with him. And like Moses and Elijah (Exodus chapter 19; 1 Kings 19:8-18), he went up a high mountain to pray.
Moses and Elijah lived long before this event happened. Perhaps they came down from heaven to meet Jesus. Or perhaps Jesus and the disciples went into *heaven (2 Corinthians 12:2). We do not know.
The disciples saw bright light and then they saw a cloud. These things showed that God was present. The disciples were afraid. But still, they wanted to be there.
The voice that came from the cloud was God‘s voice. He repeated his words in Mark 1:11. And he told the *disciples that they must listen carefully to Jesus‘ words. They had wanted to stay there with Moses and Elijah. But God had sent Jesus to teach them. And Jesus would teach them everything that they needed to know.
Then the cloud went away, and the *disciples were alone with Jesus.
Jesus told the disciples that they must not speak about this event yet. They must keep it secret. But when he became alive again, they could speak about it. The disciples could not understand Jesus‘ words. But they knew that those words were important.