8 “John stood, and two of his disciples.” Behold two of John's disciples: since John, the friend of the Bridegroom, was such as he was, he sought not his own glory, but bore witness to the truth. Did he wish that his disciples should remain with him and not follow the Lord? Rather he himself showed hisdisciples whom they should follow. For they accounted of him as though he were the lamb; and he said, “Why do you give heed to me? I am not the lamb; behold the Lamb of God,” of whom also he had already said, Behold the Lamb of God. And what benefit does the Lamb of God confer upon us? “Behold,” he says, “who takes away the sin of the world.” The two who were with John followed Him when they heard this.
Source: Tractates on the Gospel of John (New Advent)