God acknowledged Jesus as his son. We have the words of witnesses that say that God spoke with a voice that could be understood by people and confirmed that Jesus was his son. He also commanded that people should listen to Jesus.
God himself affirmed that Jesus was his son.
On two occasions he spoke directly to the people who were with Jesus saying “This is my son whom I love”. (Matthew 3:17 and 17:5; Mark 1:11 and 9:7; Luke 3:22 and 9:35)
Mark tells us that when God spoke at the Transfiguration he said “This is my son, the beloved. Listen to him!” (Mark 9:7)