John 1:37

"And the two disciples heard him, and followed Jesus." Yet John had other disciples, but they not only did not "follow Jesus," but were even jealously disposed towards him. "Rabbi," says one, "He that was with thee beyond Jordan, to whom thou barest witness, behold, the same baptizeth, and all men come unto him." And again they appear bringing a charge against him; "Why do we fast, but thy disciples fast not?" But those who were better than the rest had no such feeling, but heard, and at once followed; followed, not as despising their teacher, but as being most fully persuaded by him, and producing the strongest proof that they acted thus from a right judgment of his reasonings. For they did not do so by his advice, that might have appeared suspicious; but when he merely foretold what was to come to pass, that "He should baptize with the Holy Ghost, [and with fire,]" they followed. They did not then desert their teacher, but rather desired to learn what Christ brought with Him more than John. And observe zeal combined with modesty. They did not at once approach and question Jesus on necessary and most important matters, nor were they desirous to converse with Him publicly, while all were present, at once and in an off-hand manner, but privately; for they knew that the words of their teacher proceeded not from humility, but from truth.

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 saith unto them, "What seek ye?" 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 cleave 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 thy 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.

John having borne witness that Jesus was the Lamb of God, the disciples who had been hitherto with him, in obedience to his command, followed Jesus: And the two disciples heard him speak, and they followed Jesus.

(in loc.) Observe then, that it was upon those who followed Him, that our Lord turned His face and looked upon them. Unless thou by thy good works follow Him, thou shalt never be permitted to see His face, or enter into His dwelling.