John 2:7 - Matthew Poole's English Annotations on the Holy Bible

Either the water was defiled by some persons washing in it, or else the vessels were not full. Our Lord commands them to be filled (the water pots, not wine vessels) with water, pure water; he commands them all to be filled by the servants, who could attest the miracle, that there was nothing in the vessels but pure water. Here was no new creature to be produced; he doth not therefore command the production of wine out of nothing; but only the transformation of a creature already existent into a creature of another kind. The servants dispute not his command, nor ask any reason of his command, but yield that ready and absolute obedience which we all of us owe to Divine precepts. They fill them, and so full that they could hold no more.