Parsahat צו Leviticus 6:2 –
Leviticus 6:2 “Command Aaron and his sons, saying: This is the law of the burnt-offering: it is that which goeth up on its firewood upon the altar all night unto the morning; and the fire of the altar shall be kept burning thereby. ”
Megilah 21a: “all night unto the morning”. This teaches that the entire night is fit for burning fats and entrails
Torah Temimah Colloquial Translation on Note #7:
The Talmud learns this from the extra language in the verse (all night/until the morning). It would have been sufficient for the verse to state “all night”. If the verse only stated “all night”, one could infer that all night does not mean the entire night rather only a portion of the night. In truth we see examples where all (כל) indicates a part as in the verse referring to King Saul (Samuel I 28:20): “ Then Saul fell straightway his full length upon the earth, and was sore afraid, because of the words of Samuel; and there was no strength in him; for he had eaten no bread all the day, nor all the night.” A later verse explains that he did eat at night. Thus we see that כל can refer to the entirety or to a portion. Until the morning is not superfluous, rather it teaches us that the burning of fats and entrails is valid the entire night. Refer to the commentary of the Taz to Orach Chaim Siman תקפח. Refer also to what in written on verse 8.
Refer also to the first Mishnah in Berachot that lists all the things that are valid all night except that the Rabbis enacted a safeguard to prevent one from transgressing by only allowing one to perform these commandments until midnight. Rashi comments on this Mishanh that the Rabbis did not make this decree regarding the burning of fats and entrails.
The reason why the Rabbis made an exception for the burning of fats and entrails is unclear. A possible reason for this is the commentary of the Taz to Yoreh Deah Siman קיז and the Kesef Mishnah: “The Rabbis do not have the power to forbid anything that the Torah permits.” Because the verse here explicitly permits it as it says “all night until the morning” as explained above, however, Rambam in Chapter four of the laws of sacrifices disagrees with Rashi. For further insight refer to the Tosafot Yom Tov and Shnot Eliyahu on the first Mishnah in Berachot.
It is clear that the burning of fats and entrails is not obligatory in that they must be burned at night, rather one is permitted to burn them at night for it is sufficient if they were consumed during the day. Regarding what the Talmud says in the beginning of chapter four of Berachot (26b), that the three daily prayers correspond to the three daily sacrifices. The evening prayer corresponds to the burning of fats and limb which could b done all night. What was said above clearly explains why the evening service is optional because it corresponds to an optional sacrifice. When it says that the fats and entrails are offered at night, it means that that one is allowed to offer them at night. If they were consumed during the day, there is no obligation to leave them to be offered at night.
Another parallel between the evening service and the burning of the fats and entrails is that the time for both is the entire night. The Rabbis did not enact a safeguard for the evening service as explained in the Talmud Berachot. Similarly they did not enact a fence for the burning of fats and entrails to which the evening service corresponds. See also the Beit Yosef to Orach Chaim 233.
Editors note: The Torah Temimah discusses a fundamental principle of rabbinic law. The Rabbis do not have the power to forbid what the Torah explicitly permits as in the case discussed here. Where the Torah does not explicitly permit something, the Rabbis have the power to enact safeguards to prevent one from sinning. Even in such a case, they cannot prohibit the item or action on a biblical level. They can place a limitation on the person forbidding them to benefit from the item or performing an action. For example, when the Rabbis enacted the safeguard of not eating fowl and milk, they did not say that the Torah also refers to birds when it prohibits boiling a calf in its mother’s milk for that would violate the prohibition of adding a law to the Torah. They placed a restriction on people not to eat fowl and milk together. Another means, by which, the Rabbis prevent one from performing what the Torah permits is telling the person to refrain from doing the act (שב ואל תעשה) as in the case of not blowing the shofar when Rosh Hashanah falls on Shabbat. See Leviticus 12:3 note 14 where he expresses a similar idea with respect to circumcision on Shabbat.
 28:23-25 But he refused, and said: ‘I will not eat.’ But his servants, together with the woman, urged him; and he hearkened unto their voice. So he arose from the earth, and sat upon the bed. And the woman had a fatted calf in the house; and she made haste, and killed it; and she took flour, and kneaded it, and did bake unleavened bread thereof; and she brought it before Saul, and before his servants; and they did eat. Then they rose up, and went away that night.
 Halacha 5 note 5: referring to blowing shofar on Shabbat
 O.V. To distance a person from transgressing: While the Mishnah lists the burning of fats and entrails, Rashi comments that this Mishnah cites it as example of something that is valid all night. Thus is it not included in the list of acts, which that Rabbis forbade after midnight that follows. The Talmud in Megilah (20b) also supports this. Other commentators disagree with Rashi stating the Mishnah in Berachot includes it in the list of things that are forbidden after midnight.
 Halacha 2: Any animal whose enablers ( in Hebrew מתיריו) were offered during the day can be brought to the altar all night … In order to distance from transgression, the Rabbis said that one is not allowed to burn the entrails and limbs of the burnt offering until midnight.