9 Let us see what follows: “Behold the Lamb of God.” This John said, and the two disciples heard him speak, and followed Jesus. Then Jesus turned and saw them following, and says unto them, “What do you seek?” And they said, “Rabbi (that is to say, being interpreted, Master), where dwellest Thou?” They did not follow Him in such manner as that they should cleave to Him; for it is plain when they clave unto Him, for He called them from the ship. For one of the two was Andrew, as you have just heard, and Andrew was the brother of Peter; and we know from the Gospel that the Lord called Peter and Andrew from the ship, saying, “Come ye after me, and I will make you fishers of men.” And from that time they clave unto Him, so as not to go away.
On the present occasion these two followed Him, not as those who were not again to leave Him, but to see where He dwelt, and to fulfill the Scripture: “Let your foot wear out the threshold of His doors; arise to come to Him continually, and be instructed in His precepts.” He showed them where He dwelt: they came and remained with Him. What a blessed day they spent, what a blessed night! Who can make known to us those things which they heard from the Lord? Let us also build in our heart, and make a house into which He may come and teach us, and have converse with us.
Source: Tractates on the Gospel of John (New Advent)