John Gill Commentary Luke 22:7

"And the day of unleavened bread came, on which the passover must be sacrificed." — Luke 22:7 (ASV)

Then came the day of unleavened bread
The first of them, the fourteenth day of the month Nisan: when the passover must be killed ;
that is, the passover lamb, as the Persic version renders it; and which, according to the law in (Exodus 12:6) was to be done between the two evenings; (See Gill on Matthew 26:17).