Discrepancy between Leviticus 23:6 and Matthew 26:17?

Leviticus 23:6 says - "And on the fifteenth day of the same month is the Feast of Unleavened Bread..."

However, Matthew 26:17 says - "Now on the first day of the Feast of Unleavened Bread the disciples came to Jesus, saying to Him, "Where do You want us to prepare for You to eat the Passover?"

How can these 2 verses be reconciled?

The meaning of words can change over a period of time especially over hundreds of years. Passover may have been first used for one day, but the term later was used for that one day and the seven days of the feast of unleavened bread which followed that one day. Each of the two verses need to be interpreted in their own context to understand the meaning of its words when written.

Comparing Scripture with Scripture, Luke, who was also the human writer of the book of Acts, clearly used the Greek word pascha to refer to either the entire period--the one day of Passover and the Feast of Unleavened Bread or as an acceptable name for the Feast of Unleavened Bread. Luke wrote: “Now the feast of unleavened bread drew nigh, which is called the Passover” (Luke 22:1). At Ezekiel 45:21, the Passover is referred to as “a feast of seven days.” In Ezekiel 45:21, the name “Passover” was clearly used for or used to include the feast of Unleavened Bread, which is a feast of seven days. In Matthew 26:17, the name “Passover” was used for a time described as “the first day of the feast of unleavened bread.” After Jesus and his disciples had already observed the feast of Passover (Luke 22:14-15; John 13:1), the same Greek word was still used for a time when the feast of unleavened bread was in progress (John 18:28).

The Problem: Leviticus specifies that the Passover occurs on the fourteenth day of the month, while the Feast of Unleavened Bread begins on the fifteenth (Leviticus 23:4-6)—yet Matthew’s account (Matthew 26:17-19) places preparation activities on “the first day of Unleavened Bread.”

Resolution:
The Jews counted days sundown to sundown.

The paschal lamb was slaughtered in the afternoon of the fourteenth day and eaten after sunset, (Exodus 12:5-10), technically extending the Lord's Passover into the first day of festival of unleavened bread. The festival of unleavened bread began with the Passover meal at or after sunset following the fourteenth day.

By NT times, the fourteenth day, the day of preparation for the feast, is sometimes spoken of as the 'first day of unleavened bread, when they killed the passover lamb' prior to the feast (see Mark 14:12).

So while Leviticus 23:6 would put “the first day of the Unleavened Bread” on the fifteenth of Nisan, Mark’s (and so Matthew's description as well) describes the fourteenth of Nisan—the slaughtering of the lambs and making preparations for the paschal meal. The terms Passover and feast of unleavened bread appear to be used interchangeably for the whole festival, including both the paschal supper and the seven days of unleavened bread.

Rob