John 5:34

But I receive not testimony from man
He stood in no need of an human testimony, nor did he rest the truth of his deity and divine sonship thereon: he had other and greater testimonies to produce; as he needed not that any man should testify of man to him, he had no need that any man should testify of him; and if the testimony of men was received, as this of John could not well be objected to, the testimony of God is greater, and which he had; and therefore should not have mentioned John's for his own sake:

but these things I say, that ye might be saved;
that is, he produced this testimony of John, who was a person of so great a character among them, that they might be induced by it to believe in him as the Messiah; and so be saved from that ruin and destruction, that would come upon their nation, city, and temple, for their rejection and disbelief of him.