How did they burn the remains of the paschal lamb in the morning in Exodus 12:10?

Question

Exodus 12:10 NASB

10 And you shall not leave any of it over until morning, but whatever is left of it until morning, you shall completely burn with fire.

The next morning would be the first day of the feast of unleavened bread which would have rendered it unlawful to burn the remains.

Leviticus 23:6-7 NASB

6 Then on the fifteenth day of the same month there is the Feast of Unleavened Bread to the Lord; for seven days you shall eat unleavened bread. 7 On the first day you shall have a holy convocation; you shall not do any laborious work.

How did they burn the remains in the next morning?

Answer 1

There are many examples of this such as:

• Matt 12:3, 4 - Jesus replied, “Have you not read what David did when he and his companions were hungry? He entered the house of God, and he and his companions ate the consecrated bread,a which was not lawful for them to eat, but only for the priests.
• Matt 12:5 - Or haven’t you read in the Law that on the Sabbath the priests in the temple break the Sabbath and yet are innocent?
• Luke 13:14-16 - But the synagogue leader was indignant that Jesus had healed on the Sabbath. “There are six days for work,” he told the crowd. “So come and be healed on those days and not on the Sabbath.” “You hypocrites!” the Lord replied. “Does not each of you on the Sabbath untie his ox or donkey from the stall and lead it to water? Then should not this daughter of Abraham, whom Satan has kept bound for eighteen long years, be released from her bondage on the Sabbath day?”
• John 7:22-24 - But because Moses gave you circumcision, you circumcise a boy on the Sabbath (not that it is from Moses, but from the patriarchs.) If a boy can be circumcised on the Sabbath so that the law of Moses will not be broken, why are you angry with Me for making the whole man well on the Sabbath? Stop judging by outward appearances, and start judging justly.”

All these, including the example quoted by the OP in Ex 12:10 vs Lev 23:6, 7 are examples of conflicts in the Torah. However, as shown above, the application of the Torah was practical - there were clear hierarchies; health and life was more important than ceremonial requirements.

In the particular case of Ex 12:10 vs Lev 23:6, 7 is perfect example of such - burning a dead carcass was essential for maintaining ceremonial (and now we also know, hygienic) standards. Thus, the remains of the Lamb carcass would have been burned on the day after Passover.

Ellicott observes this:

(10) Ye shall let nothing of it remain.—That there might be neither profanation nor superstitious use of what was left. (Comp. the requirement of the Church of England with respect to the Eucharistic elements.)

That which remaineth—i.e., the bones and such particles of flesh as necessarily adhered to them. These were to be at once totally consumed by fire. Thus only could they be, as it were, annihilated, and so secured from profanation.

Benson is similar:

That which remaineth ye shall burn with fire — To prevent its corruption, and the profane abuse of it.

The Pulpit commentary has this:

That which remaineth - i.e., the bones, and any small fragments of the flesh necessarily adhering to them. Ye shall burn with fire. Thus only could its complete disappearance, and seeming annihilation be secured. It does not appear that this burning was viewed as a sacrificial act. Exodus 12:10

Answer 2

The 15th day of Aviv starts Chag HaMatzot (Festival of Unleavened Bread) referenced in [Leviticus 23:6-7] which begins בָּעֶ֔רֶב Ba-Erev “In-Evening” (sunset) of the 14th of Aviv - NOT the sunrise of the 14th day. [Exodus 12:10] occurs during Boqer בֹּקֶר (sunrise) of Pesach - still the 14th Day of Aviv.

the "Pass [over]" plague only occurred בָּעֶ֔רֶב Ba-Erev (in-[the] evening) at the start of the 14th Day of Aviv, the Israelites fled Mitzrayim at night לַ֗יְלָה early on the 14th Day of Aviv [Exodus 12:31].

At sunrise on Pesach (when the remains of the Paschal Lamb are burned) the day is still the 14th. - as stated in [Exodus 12:10] (וְלֹֽא־תוֹתִ֥ירוּ מִמֶּ֖נּוּ עַד־בֹּ֑קֶר וְהַנֹּתָ֥ר מִמֶּ֛נּוּ עַד־בֹּ֖קֶר בָּאֵ֥שׁ תִּשְׂרֹֽפוּ) - Boqer בֹּקֶר is a SUNRISE - not a sunset.

Exodus 12:18 states

"In the first [month], on the fourteenth day of the month in the evening, you shall eat unleavened cakes, until the twenty first day of the month in the evening." ( בָּֽרִאשֹׁ֡ן בְּאַרְבָּעָה֩ עָשָׂ֨ר י֤וֹם לַחֹ֨דֶשׁ֙ בָּעֶ֔רֶב תֹּֽאכְל֖וּ מַצֹּ֑ת עַ֠ד י֣וֹם הָֽאֶחָ֧ד וְעֶשְׂרִ֛ים לַחֹ֖דֶשׁ בָּעָֽרֶב )

Full Moon appeared "in the evening" of 14th / Start of 15th Day of Aviv - starting the celebration of Chag HaMatzot.

[Exodus 12:34] "The people picked up their dough when it was not yet leavened, their leftovers bound in their garments on their shoulders." ( וַיִּשָּׂ֥א הָעָ֛ם אֶת־בְּצֵק֖וֹ טֶ֣רֶם יֶחְמָ֑ץ מִשְׁאֲרֹתָ֛ם צְרֻרֹ֥ת בְּשִׂמְלֹתָ֖ם עַל־שִׁכְמָֽם )

[Exodus 12:39] "They baked the dough that they had taken out of Egypt as unleavened cakes, for it had not leavened, for they were driven out of Egypt, and they could not tarry, and also, they had not made provisions for themselves." ( וַיֹּאפ֨וּ אֶת־הַבָּצֵ֜ק אֲשֶׁ֨ר הוֹצִ֧יאוּ מִמִּצְרַ֛יִם עֻגֹ֥ת מַצּ֖וֹת כִּ֣י לֹ֣א חָמֵ֑ץ כִּי־גֹֽרְשׁ֣וּ מִמִּצְרַ֗יִם וְלֹ֤א יָֽכְלוּ֙ לְהִתְמַהְמֵ֔הַּ וְגַם־צֵדָ֖ה לֹֽא־עָשׂ֥וּ לָהֶֽם )

• Evening of 14th / Start of 15th | day #1.
• Evening of 15th / Start of 16th | day #2.
• Evening of 16th / Start of 17th | day #3.
• Evening of 17th / Start of 18th | day #4.
• Evening of 18th / Start of 19th | day #5.
• Evening of 19th / Start of 20th | day #6.
• Evening of 20th / Start of 21st | day #7.
• Evening of 21st of Aviv ended the 7-day festival of Chag HaMatzot.