World Wide Study Bible
a Bible passage
25. The baptism of John—meaning his whole mission and ministry, of which baptism was the proper character.
whence was it? from heaven, or of men?—What wisdom there was in this way of meeting their question will best appear by their reply.
If we shall say, From heaven; he will say unto us, Why did ye not then believe him?—"Why did ye not believe the testimony which he bore to Me, as the promised and expected Messiah?" for that was the burden of John's whole testimony.