Once again the “Verily, verily” of deeper truth. “We speak that we do know” is in sharp contrast to their formal teaching of matters external to the truth. The plural is not usual in the language of Christ, and the immediate passage to the singular forbids us to accept the usual grammatical explanation that it is the plural of majesty. He apparently joins others with Himself, — those who have spoken and known and testified, and whose testimony has been rejected by the Jews. We have to think of him whose life-work was to bear witness of the Light (John 1:8), and of the band of disciples who form a little school round their Master, and who in Jerusalem, as in Galilee, testified of Him; and it may even be that in the house and presence of one of that band this conversation took place (comp. John 3:2). They knew the power of the new life, and had been baptised of water and of spirit. In their measure and degree, as He in fulness, they spake what they knew, and testified what they had seen. (Comp. John 15:27.)
And ye receive not our witness — i.e., “ye Jews,” the teachers, of whom Nicodemus was one, the representatives of His own who received Him not (John 1:11). This attitude of the mind which refused to accept the evidence of witnesses as to things they had known and seen was of the essence of unbelief, and made further revelation impossible. When the will closed the faculty of faith, it left open no access for fuller spiritual truth.