There is another... — i.e., the Father. The reference to the Baptist is excluded by the words which follow. The difficulty which has been seen in this indirect reference to the Father is removed if we connect the words closely with those preceding them. The point is in the fact that another, different in personality from Himself, bore witness of Him. (Comp. John 8:50; Matthew 10:28, et al.)
I know... — This has seemed to have a natural meaning if it is the authority given to John’s witness, but to be less fitting if applied to the Father’s. In two of the oldest MSS., and some of the earliest versions, we read “ye know,” and this has been adopted by some modern editors; but the origin of this reading is obvious, and there is no sufficient reason for departing from the common text. Its meaning is quite in harmony with the relation of the Son to the Father, which has been dwelt upon. The Father beareth witness, is bearing witness (comp. John 5:37), in the unity of work which Son and Father alike work (John 5:17; John 5:19-20; John 5:30), and the Son knows that His power to do this work can come from no other source. His own nature responds to the Father’s voice; He knows it to be true. (Comp. John 3:33.)