John the Apostle
John 1:51BSB·traditional attribution

Then He declared, “Truly, truly, I tell you, you will all see heaven open and the angels of God ascending and descending on the Son of Man.”

John Calvin Reformed @genevareformer

51. You shall see heaven opened. They are greatly mistaken, in my opinion, who anxiously inquire into the place where, and the time when, Nathanael and others saw heaven opened; for he rather points out something perpetual which was always to exist in his kingdom.

Matthew Henry Presbyterian @wholebiblehenry

We have here the call of Philip and Nathanael. I. Philip was called immediately by Christ himself, not as Andrew, who was directed to Christ by John, or Peter, who was invited by his brother. God has various methods of bringing his chosen ones home to himself. But, whatever means he uses, he is not tied to any. 1. Philip was called in a preventing was: Jesus findeth Philip.

Commenting on John 1:43-51

John Gill Reformed Baptist @doctorgill

And he saith unto him, verily, verily, I say unto you,.... Not only to Nathanael, but to the rest of the disciples that were then with him; and to show himself to be the "Amen", and faithful witness, as well as more strongly to asseverate what he was about to say, he doubles the expression: hereafter you shall see heaven open; either in a literal...