Albert Barnes Commentary Matthew 26:19

"And the disciples did as Jesus appointed them; and they made ready the passover." — Matthew 26:19 (ASV)

They made ready the Passover. That is, they procured a paschal lamb, multitudes of which were kept for sale in the temple; they procured it to be killed and flayed by the priests, and the blood to be poured at the altar; they roasted the lamb, and prepared the bitter herbs, the sauce, and the unleavened bread. This was done, it seems, while our Lord was absent, by the two disciples.