What promise did Jesus make that were confirmed by his resurrection?

Jesus promised that he would rise from the dead after three days, affirming his power over sin and death (as seen in Mark 8:31). His resurrection confirmed this promise, demonstrating that he is the Messiah and offering believers the hope of eternal life. It also validated his teachings and authority, establishing a foundation for the Christian faith. Ultimately, his resurrection serves as a guarantee of the future resurrection for all who believe in him.