Albert Barnes Commentary John 6:36

"But I said unto you, that ye have seen me, and yet believe not." — John 6:36 (ASV)

But I said to you. This He said, not in so many words, but in substance, in John 6:26. Though they saw Him, and had full proof of His divine mission, yet they did not believe. Jesus then proceeds to state that, although they did not believe on Him, yet His work would not be in vain, for others would come to Him and be saved.