The Catechism in Questions & Answers

97. How did John the Baptist describe Jesus Christ?

When Jesus came to John, the latter said: “‘Behold! The Lamb of God who takes away the sin of the world!’ Again, the next day, John stood with two of his disciples, and looking at Jesus as He walked, he said, ‘Behold the Lamb of God!’ The two disciples heard him speak, and they followed Jesus” (cf. John 1: 29, 35-37).