In John 1:51, the author recounts to us the words of Jesus as he gathered disciples.
John 1:43 The next day He (Jesus) purposed to go into Galilee, and He found Philip. And Jesus said to him, “Follow Me.”
44 Now Philip was from Bethsaida, of the city of Andrew and Peter.
45 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.”
46 Nathanael said to him, “Can any good thing come out of Nazareth?” Philip said to him, “Come and see.”
47 Jesus saw Nathanael coming to Him, and said of him, “Behold, an Israelite indeed, in whom there is no deceit!”
48 Nathanael said to Him, “How do You know me?” Jesus answered and said to him, “Before Philip called you, when you were under the fig tree, I saw you.”
49 Nathanael answered Him, “Rabbi, You are the Son of God; You are the King of Israel.”
50 Jesus answered and said to him, “Because I said to you that I saw you under the fig tree, do you believe? You will see greater things than these.”
51 And He said to him, “Truly, truly, I say to you, you will see the heavens opened and the angels of God ascending and descending on the Son of Man.”
Note how Jesus addresses Nathanael. He says, “Behold, an Israelite indeed, in whom their is no deceit.” This statement is preparatory for what follows, for one familiar with his Bible would immediately get the reference to Jacob/Israel, the deceitful one. Jacob’s name comes from the root עקב, which means “to attack at the heel/from behind”, deceitfully (see BDB, 784). Nathanael, it appears, is very much unlike Jacob in that he is without guile. This is preparatory, a framing of the conversation that will take place hereafter. The conversation is not so much about who Nathanael is but about who Jesus is and what he has come to do.
The author has just said, in the words of Philip, that the one about whom the Torah and Prophets had spoken was here, and that he could be seen (1:45). When Nathanael sees him, he quickly discovers that Jesus had seen him! Not only did he see into the mind of Nathanael and discern his character, but he “saw” him under the fig tree. This micro-miracle would be enough for Nathanael to believe, but Jesus is not done. While Nathanael is portrayed as a deceit-less Jacob/Israel, Jesus himself is portrayed or portrays himself as a new Jacob/Israel, the true “seed”.
Jesus, in referring to Nathanael as “an Israelite”, is prompting the reader to think about Jacob/Israel in general, but his remark in v.51 is the clincher, and the real point of the passage. He doesn’t call Nathanael to follow him. Philip has already done so. What he asks of all who saw him (note plural verb) is that they simply bear witness to the “greater works” of Jesus and recognize the orienting of God’s promises made to Israel toward Jesus, the seed of Israel (cf. Gal. 3:16ff).
In v.51, Jesus addresses everyone standing there, “You (plural) will see the heavens opened and the angels of God ascending and descending upon the Son of Man.” The key to this passage is its allusion, but what is he alluding to here? If we look at Genesis 28, we will get our answer. Jesus had earlier alluded to Jacob in his description of Nathanael, and here he alludes to Jacob again. Jacob is at Bethel (בֵּית אֵל = “house of God”), and he lies down to sleep. He dreams, and he sees the heavens opened and the angels of God are “ascending and descending” on either a ladder or upon Jacob himself. The combination in Hebrew is בּוֹ (beth preposition + 3ms proniminal suffix “him” or “it”), which can mean either “on it” or “on him”. The text is ambiguous. Are the angels ascending and descending on Jacob or the ladder?
וְהִנֵּה֙ מַלְאֲכֵ֣י אֱלֹהִ֔ים עֹלִ֥ים וְיֹרְדִ֖ים בּֽוֹ׃
The English versions all read “it”, referring to the ladder, but Jesus reads it as “him”, that is, the angels are ascending and descending on Jacob. In doing so, he makes his point. In Gen. 28 Jacob (at Beth-el, the House of God) and his “seed” receive the promise of the land.
וְהִנֵּ֙ה יְהוָ֜ה נִצָּ֣ב עָלָיו֮ וַיֹּאמַר֒ אֲנִ֣י יְהוָ֗ה אֱלֹהֵי֙ אַבְרָהָ֣ם אָבִ֔יךָ וֵאלֹהֵ֖י יִצְחָ֑ק הָאָ֗רֶץ אֲשֶׁ֤ר אַתָּה֙ שֹׁכֵ֣ב עָלֶ֔יהָ לְךָ֥ אֶתְּנֶ֖נָּה וּלְזַרְעֶֽךָ׃
“And behold, the Lord was standing above it (or “over him”, note again the ambiguity), and he said, I am the LORD, the God of Abraham, your father, and the God of Isaac. The land upon which are lying, to you I will give it and to your seed.”
According to John/Jesus, the “seed” is now here, and he is about to embark on a mission to bring the Kingdom of God to men, to conquer the land, and as with Jacob the ministering spirits will minister to him as he vanquishes the enemy (Matt. 4:11; Heb. 1:14). Jesus is the focal point of God’s promises to man, for he is the “seed” of Abraham. All God’s promises are “yes” in Him…(2 Cor. 1:20), and those who receive him, as heirs with him, receive all of God’s promises to Israel. After all, he is “The Son”, and “The Son” receives the inheritance.
How does John 1:51 and Genesis 28 relate to John 2? For now, you put the pieces together…