Luke 22:7

‘And the day of unleavened bread came, on which the passover must be sacrificed.'

Note here how Passover can be called ‘the day of unleavened bread' even though it is the day before ‘the Feast of Unleavened Bread' began. This was because it was the day for removing unleavened bread from their houses. On this day they would ensure that any remaining leavened bread had been removed, so that the period of being free from leaven could begin. Luke is thus stressing the connection of the Feast with what is about to happen. The sinless Lamb of God Who had come to take away the sins of the world (John 1:29; 1 Corinthians 5:7) had come to be offered up. His hour had come.