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. This was impartial evidence in the case, and hence he so particularly dwells upon it.John stood - Or was standing. This was probably apart from the multitude.
Two of his disciples - One of these was Andrew John 1:40, and it is not improbable that the other was the writer of this gospel.

The next day - After that mentioned John 1:29.
Two of his disciples - One of them was Andrew, John 1:40, and it is very likely that John himself was the other; in every thing in which he might receive honor he studiously endeavors to conceal his own name.

(15) Again the next day after John stood, and two of his disciples;
(15) John gathers disciples not to himself, but to Christ.

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 John 1:40 and very likely the other was the Evangelist John, the writer of this Gospel, who always chooses to conceal himself. John the Baptist stood, and these disciples by him, in some certain place near Jordan, where he was preaching and baptizing.

John stood--"was standing," at his accustomed place.

Again the next day after, John stood, and two of his disciples. In John 1:19-28, the account is given of the visit of the priests and Levites, sent by the Sanhedrim to John. "The next day" after this, John sees Jesus and points him out as the Lamb of God, giving a discourse of which, in John 1:19-34, we have a synopsis. On the "next day" after this, the third day after the deputation of the Sanhedrim, and the second after the return of Jesus from the wilderness, Jesus stood with two of his disciples. One of these two, we learn from John 1:40, was Andrew; the other, we have reason to believe, was John, the apostle.