This beginning of his signs Jesus did in Cana of Galilee, and revealed his glory; and his disciples believed in him.
Believed on him - This does not mean that they did not believe on him beforehand, but that their faith was confirmed or strengthened. They saw a miracle, and it satisfied them that he was the Messiah. “Before this” they “believed” on the testimony of John, and from conversation with Jesus John 1:35-51; now they saw that he was invested with almighty power, and their faith was established.