But should any one say, “If on the first day of unleavened bread the disciples of our Saviour prepare the Passover, on that day then should we also celebrate the Passover;” we answer, that this was not an admonition, but a history of the fact. It is what took place at the time of the saving Passion; but it is one thing to relate past events, another to sanction and leave them an ordinance to posterity. Moreover, the Saviour did not keep His Passover with the Jews at the time that they sacrificed the lamb. For they did this on the Preparation, when our Lord suffered. Therefore they entered not into the hall of Pilate, that they might not be defiled, but might eat the Passover. (John 18:28.) For from the time that they conspired against the truth, they drove far from them the Word of truth. Nor on the first day of unleavened bread, on which the Passover ought to be sacrificed, did they eat their accustomed Passover, for they were intent upon something else, but on the day after, which was the second of unleavened bread. But our Lord on the first day of unleavened bread, that is, on the fifth day of the week, kept the Passover with His disciples.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).