So after he had washed their feet
Not Peter's only, but the rest of the disciples also: some have thought, that he washed only the feet of some of them, and not all; but it seems, by this expression, that he performed this service to each of them: and when he had gone through it with everyone of them:
and had taken his garments,
and put them on,
and was sat down again;
at the table with his disciples, supper not being yet ended; when having done his work as a servant, he reassumes the air and authority of Lord and master, and begins to teach and instruct, into the design and use of what he had been doing, which he introduces by putting this question;
he said unto them, know ye what I have done to you?
They knew the outward action he had done to them, that he had washed their feet; but, as yet, they did not know the mystery of it, Christ's design in it, and what he would have them learn from it.