John the Apostle
John 15:26BSB·traditional attribution

When the Advocate comes, whom I will send to you from the Father—the Spirit of truth who proceeds from the Father—He will testify about Me.

Geneva Bible Notes Reformed

But when the Comforter is come, whom I will send unto you from the Father, [even] the Spirit of truth, which proceedeth from the Father, he shall testify of me: (8) We will surely stand against the rage of the wicked by the inward testimony of the Holy Spirit.

John Calvin Reformed

26. But when the Comforter is come. After having explained to the apostles that the Gospel ought not to be less highly valued by them, because it has many adversaries, even within the Church itself; Christ now, in opposition to the wicked fury of those men, produces the testimony of the Spirit, and if their consciences rest on this testimony, they will never be shaken...

Albert Barnes Presbyterian

Verse 26. (d) "Comforter is come" (e) "he shall testify of me"