Leviticus 7:16

But if his hallowed sacrifice be a vow or a free-will gift, the sacrifice may be (partly) eaten on the day when it is offered, and the remainder may be eaten on the day following at evening.

a vow which is uttered in distress a pledge a spirit of largess prompted him to bring an offering to God. This is neither the fulfillment of a vow, nor an offering of gratitude.

of his offering The verb is an infinitive of the hif‘il form.

the day following i.e., the day following the day of his offering.

The vav in what remains is a general-purpose connective particle, like the f of Arabic.

AND ON THE MORROW ‘V’HANOTHAR’ (AND THAT WHICH REMAINETH) OF IT SHALL BE EATEN. “The letter vav [in the word v’hanothar — ‘and’ that which remaineth] is redundant [thus the meaning of the verse is: “and on the morrow, that which remaineth of it shall be eaten”]. There are many examples of this in Scripture, such as: and these are the children of Zibeon: ‘v’ayah’ (and Ajah) and Anah. in v’ayah (“and” Ajah) is redundant. See in Vol. I, p. 440. So also: to give ‘v’kodesh’ (‘and’ the Sanctuary) and the host to be trampled upon.” in v’kodesh (“and” the Sanctuary) is here redundant. This is Rashi’s language, and so did Rabbi Abraham ibn Ezra interpret the verse.
In my opinion the meaning of the verse is as follows: Since He said, it shall be eaten on the day that he offereth his offering, and on the morrow, this might imply that it is a commandment that it [the peace-offering] be eaten in two days, [namely] that he should eat part of it on the first day, and should leave part of it to be eaten on the morrow. Therefore He explained again, ‘and’ that which remaineth is to be eaten on the first day and also on the morrow [if by chance it was not all eaten on the first day]. But he is not to leave some over intentionally, nor is he permitted to leave it all over to be eaten on the second day. Rather, it is a commandment that he should eat it on the first day, and that which is left over by chance, should be eaten on the morrow previously mentioned.
This matter we have learned from the words of our Rabbis, who have said in the Torath Kohanim: 12:11-12. “On the day that he offereth it, shall it be eaten. It is a commandment that it be eaten thereof during the first day. I might think that he is commanded to eat the whole of it; Scripture therefore says, and on the morrow. I might then think that it is a commandment to eat it in two days; Scripture therefore states, and that which remaineth — if it remains, it remains [i.e., it may still be eaten]. If [we are to go by the expression] and that which remaineth, I might think that if he left it all over for the second day it is invalid [since that does not come under the term “remaineth” which indicates only a part thereof]; Scripture therefore says [that which remaineth of it] shall be eaten, even all of it.” And even if you hold the vav in v’hanothar (and that which remaineth) to be redundant, [as Rashi explained], the verse can also be explained to mean: “and on the morrow that which remained of it [from the first day] may be eaten,” but not that he is to leave it over intentionally.
But I do not know why Rashi held the vav of the verse, to give ‘v’kodesh’ (‘and’ the Sanctuary) and the host to be trampled upon in v’kodesh (“and” the Sanctuary) is here redundant. to be redundant, since the meaning of the verse is that [the angel] is asking: “How long shall the transgression give appalment, and how long shall the Sanctuary and the host be trampled underfoot?” in v’kodesh thus stands for the repetition of the phrase ad mathai (how long), and is therefore not redundant.

ואם נדר או נדבה, if the formula used in uttering the vow included the word שלמים, an expression which refers to making payment for favours received, as I explained on 2,1, etc. In other words the expression תודה did not feature in the wording of the vow.

ביום הקריבו, on the day of his having sacrificed it, it may be eaten already, as soon as the necessary procedures have been completed.