No one has ascended to heaven but He who came down from heaven, that is, the Son of Man who is in heaven.
John 3:13
Surrounding context
3:12 If I have told you earthly things and you do not believe, how will you believe if I tell you heavenly things?
3:13 No one has ascended to heaven but He who came down from heaven, that is, the Son of Man who is in heaven.
3:14 And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up,