The next day again John was standing with two of his disciples,
This is now the third day, with the first being the day the Pharisees sent to question John, and the second being the day John first identified Jesus as the Lamb of God (John 1:29).
and he looked at Jesus as he walked by and said, "Behold, the Lamb of God!"
This message is identical to the day before. It signifies that John's teaching is coming to an end, as he now points people to Jesus.
John 1:29
The next day he saw Jesus coming toward him, and said, "Behold, the Lamb of God, who takes away the sin of the world!"
The two disciples heard him say this, and they followed Jesus.
Any who truly believed in God were following not John but the message he preached, which he had received from God. Doubtless his words were clearly audible to bystanders, but those who actually heard him evidenced the fact by following Jesus.
Acts 19:1-5
...Paul passed through the inland country and came to Ephesus. There he found some disciples. And he said to them, "Did you receive the Holy Spirit when you believed?" And they said, "No, we have not even heard that there is a Holy Spirit." And he said, "Into what then were you baptized?" They said, "Into John's baptism." And Paul said, "John baptized with the baptism of repentance, telling the people to believe in the one who was to come after him, that is, Jesus." On hearing this, they were baptized in the name of the Lord Jesus.
Jesus turned and saw them following and said to them, "What are you seeking?" And they said to him, "Rabbi" (which means Teacher), "where are you staying?"
John examines the topic of seeking thoroughly, with the word appearing on nearly every page of his gospel.
John 4:23, 27
"The hour is coming, and is now here, when the true worshipers will worship the Father in spirit and truth, for the Father is seeking such people to worship him...." Just then his disciples came back. They marveled that he was talking with a woman, but no one said, "What do you seek?" or, "Why are you talking with her?"
John 5:44
How can you believe, when you receive glory from one another and do not seek the glory that comes from the only God?
John 6:24-27
When the crowd saw that Jesus was not there, nor his disciples, they themselves got into the boats and went to Capernaum, seeking Jesus. When they found him on the other side of the sea, they said to him, "Rabbi, when did you come here?" Jesus answered them, "Truly, truly, I say to you, you are seeking me, not because you saw signs, but because you ate your fill of the loaves. Do not work for the food that perishes, but for the food that endures to eternal life, which the Son of Man will give to you. For on him God the Father has set his seal."
John 18:3-6
Judas, having procured a band of soldiers and some officers from the chief priests and the Pharisees, went there with lanterns and torches and weapons. Then Jesus, knowing all that would happen to him, came forward and said to them, "Whom do you seek?" They answered him, "Jesus of Nazareth." Jesus said to them, "I AM." Judas, who betrayed him, was standing with them. When Jesus said to them, "I AM," they drew back and fell to the ground.
John 20:15-16
Jesus said to her, "Woman, why are you weeping? Whom are you seeking?" Supposing him to be the gardener, she said to him, "Sir, if you have carried him away, tell me where you have laid him, and I will take him away." Jesus said to her, "Mary." She turned and said to him in Aramaic, "Rabboni!" (which means Teacher).
Matthew 23:8
But you are not to be called rabbi, for you have one teacher, and you are all brothers.
He said to them, "Come and you will see." So they came and saw where he was staying, and they stayed with him that day, for it was about the tenth hour.
Compare verse 46.
One of the two who heard John speak and followed Jesus was Andrew, Simon Peter's brother.
He first found his own brother Simon and said to him, "We have found the Messiah" (which means Christ).
"Messiah" is Hebrew for, The Lord's Anointed. "Christ" is Greek for, Anointed.
1 Samuel 16:1, 6, 12
The LORD said to Samuel, "How long will you grieve over Saul, since I have rejected him from being king over Israel? Fill your horn with oil, and go. I will send you to Jesse the Bethlehemite, for I have provided for myself a king among his sons...."
When they came, he looked on Eliab and thought, "Surely the LORD's anointed is before him...."
And he sent and brought [David] in.... And the LORD said, "Arise, anoint him, for this is he."
1 Samuel 26:9
But David said to Abishai, "Do not destroy him, for who can put out his hand against the LORD's anointed and be guiltless?"
2 Samuel 1:14
David said to him, "How is it you were not afraid to put out your hand to destroy the LORD's anointed?"
Lamentations 4:20
The breath of our nostrils, the LORD's anointed,
was captured in their pits,
of whom we said, "Under his shadow
we shall live among the nations."
He brought him to Jesus. Jesus looked at him and said, "You are Simon the son of John. You shall be called Cephas" (which means Peter).
"Peter" (which means "A Stone")
The next day Jesus decided to go to Galilee. He found Philip and said to him, "Follow me."
Now Philip was from Bethsaida, the city of Andrew and Peter.
Philip found Nathanael and said to him, "We have found him of whom Moses in the Law and also the prophets wrote, Jesus of Nazareth, the son of Joseph."
John 5:46-47
"If you believed Moses, you would believe me; for he wrote of me. But if you do not believe his writings, how will you believe my words?"
Nathanael said to him, "Can anything good come out of Nazareth?" Philip said to him, "Come and see."
Compare verse 39.
Jesus saw Nathanael coming toward him and said of him, "Behold, an Israelite indeed, in whom there is no deceit!"
Romans 2:28-29
No one is a Jew who is merely one outwardly, nor is circumcision outward and physical. But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God.
1 Peter 2:22
He committed no sin, neither was deceit found in his mouth.
Nathanael said to him, "How do you know me?" Jesus answered him, "Before Philip called you, when you were under the fig tree, I saw you."
Nathanael answered him, "Rabbi, you are the Son of God! You are the King of Israel!"
Compare verse 38. Each on learning who Jesus really is calls Him Rabbi.
Jesus answered him, "Because I said to you, 'I saw you under the fig tree,' do you believe? You will see greater things than these."
This is a pattern in John. The Lord separates those who merely claim to believe from those who really do. But in typical Johannine fashion, this first iteration is mild: Nathanael is not condemned, but rather what he will see is even better than he imagined.
A late iteration of the pattern is the episode with Thomas, who is definitely condemned. Blessings are for those who have not seen.
John 20:29
Jesus said to him, "Have you believed because you have seen me? Blessed are those who have not seen and yet have believed."
And he said to him, "Truly, truly, I say to you, you will see heaven opened, and the angels of God ascending and descending on the Son of Man."
This refers to God appearing to Jacob at Luz in Canaan, called Bethel. God was with Jacob without his realizing it (Genesis 28:16). In Genesis 28, Jacob came to this place after surviving his encounter with Esau, and in Genesis 35 he fled to this place for refuge after his sons made them odious by killing the sons of Hamor. In reverence Jacob built an altar and anointed it with oil.
Genesis 28:11–22
And [Jacob] came to a certain place and stayed there that night, because the sun had set. Taking one of the stones of the place, he put it under his head and lay down in that place to sleep. And he dreamed, and behold, there was a ladder set up on the earth, and the top of it reached to heaven. And behold, the angels of God were ascending and descending on it! And behold, the LORD stood above it and said, "I am the LORD, the God of Abraham your father and the God of Isaac. The land on which you lie I will give to you and to your offspring. Your offspring shall be like the dust of the earth, and you shall spread abroad to the west and to the east and to the north and to the south, and in you and your offspring shall all the families of the earth be blessed. Behold, I am with you and will keep you wherever you go, and will bring you back to this land. For I will not leave you until I have done what I have promised you." Then Jacob awoke from his sleep and said, "Surely the LORD is in this place, and I did not know it." And he was afraid and said, "How awesome is this place! This is none other than the house of God, and this is the gate of heaven." So early in the morning Jacob took the stone that he had put under his head and set it up for a pillar and poured oil on the top of it. He called the name of that place Bethel, but the name of the city was Luz at the first. Then Jacob made a vow, saying, "If God will be with me and will keep me in this way that I go, and will give me bread to eat and clothing to wear, so that I come again to my father's house in peace, then the LORD shall be my God, and this stone, which I have set up for a pillar, shall be God's house. And of all that you give me I will give a full tenth to you."
Genesis 48:3–4, 9, 11, 21
And Jacob said to Joseph, "God Almighty appeared to me at Luz in the land of Canaan and blessed me, and said to me, 'Behold, I will make you fruitful and multiply you, and I will make of you a company of peoples and will give this land to your offspring after you for an everlasting possession....'"
Joseph said to his father, "They are my sons, whom God has given me here...."
And Israel said to Joseph, "I never expected to see your face; and behold, God has let me see your offspring also...."
Then Israel said to Joseph, "Behold, I am about to die, but God will be with you and will bring you again to the land of your fathers...."
Genesis 50:5, 12-13
"My father made me swear, saying, 'I am about to die: in my tomb that I hewed out for myself in the land of Canaan, there shall you bury me.' Now therefore, let me please go up and bury my father. Then I will return...."
Thus his sons did for him as he had commanded them, for his sons carried him to the land of Canaan and buried him in the cave of the field at Machpelah, to the east of Mamre, which Abraham bought with the field from Ephron the Hittite to possess as a burying place.