Theophylact of Ohrid
Catena Aurea · Lukasevangelium 22
Then came the day of unleavened bread, when the Passover must be killed. And he sent Peter and John, saying, Go and prepare us the Passover, that we may eat. And they said unto him, Where wilt thou that we prepare? And he said unto them, Behold, when ye are entered into the city, there shall a man meet you, bearing a pitcher of water; follow him into the house where he entereth in. And ye shall say unto the goodman of the house, The Master saith unto thee, Where is the guestchamber, where I shall eat the Passover with my disciples? And he shall shew you a large upper room furnished: there make ready. And they went, and found as he had said unto them: and they made ready the Passover.
He sends them for this reason to an unknown man: to shew them that He voluntarily underwent His Passion, since He who so swayed the mind of one unknown to Him, that He should receive them, was able to deal with the Jews just as He wished. But some say that He gave not the name of the man, lest the traitor knowing his name might open the house to the Pharisees, and they should have come and taken Him before that the supper was eaten, and He had delivered the spiritual mysteries to His disciples. But He directs them by particular signs to a certain house; whence it follows, And ye shall say to the goodman of the house, The Master saith, Where is the guestchamber, &c. And he will shew you an upper room, &c.