He told the disciples he WOULD BE killed and rise from the dead after three days. That was a prophecy.
If he was going to pray to God and be spared he wouldn’t have prophesied categorically that he would be killed and rise from the dead. He would have prophesied that he would be arrested, they would try to kill him, but God would save him. That would be what a true prophet would have predicted if the Qur’an is authoritative.
The Qur’an is still wrong one way or the other because Jesus prophesied that he would be killed and rise after three days, but the Qur’an says he was wrong when he predicted that. So either the Qur’an is wrong and Jesus wasn’t a true prophet or the Qur’an is wrong about God saving Jesus from death. Pick your poison!
The Gospels get it right. Jesus was a prophet, he correctly prophesied his death and resurrection. He was killed by crucifixion and rose again from the dead after three days. Virtually all Biblical historians agree to the fact that Jesus died of crucifixion.