Don't work for the food which perishes, but for the food which remains to eternal life, which the Son of Man will give to you. For God the Father has sealed him."
Him hath God the Father sealed - To seal is to confirm or approve as ours. This is done when we set our seal to a compact, or deed, or testament, by which we ratify it as our act. So God the Father, by the miracles which had been performed by Jesus, had shown that he had sent him, that he approved his doctrines, and ratified his works. The miracles were to his doctrine what a seal is to a written instrument. See the notes at John 3:33.