John the Apostle
John 1:35ESV·traditional attribution

The next day again John was standing with two of his disciples,

Matthew Henry Presbyterian @wholebiblehenry

We have in these verses an account of John's testimony concerning Jesus Christ, which he witnessed to his own disciples that followed him. As soon as ever Christ was baptized he was immediately hurried into the wilderness, to be tempted; and there he was forty days.

Commenting on John 1:29-36

John Gill Reformed Baptist @doctorgill

Again, the next day after,.... The third day from the priests and Levites having been with John, to know who he was. The Syriac, Arabic, and Persic versions, leave out the word "again": stood, and two of his disciples; one of these was Andrew, Simon Peter's brother, as appears from Joh 1:40 and very likely the other was the Evangelist John, the writer of this...

Albert Barnes Presbyterian @notesbybarnes

Verse 35. The next day. The day after his remarkable testimony that Jesus was the Son of God. This testimony of John is reported because it was the main design of this evangelist to show that Jesus was the Messiah. See the Introduction. To do this, he adduces the decided and repeated testimony of John the Baptist.