Lévitique 1:15

And the priest shall offer it upon the altar, and shall wring off its head, and burn upon the altar, and press out its blood at the side of the altar.

behead This word has no cognate: the form of beheading is known only from tradition.

its blood will be squeezed out a verb in the nif‘al form, from “you have drained” [Isaiah 51:17]

AND THE PRIEST SHALL BRING IT UNTO THE ALTAR. This “bringing” means bringing it up onto the altar, signifying that the priest is to bring up the bird onto the altar and nip off its head there, as the nipping off may only be done on top of the altar. It is for this reason that the Rabbis interpreted: “And the priest shall bring it … Could you possibly think that a non-priest could come near the altar? If so, why does it say the priest … shall nip off? It is to teach us that the nipping off be done [not with an instrument but] only by the priest himself.” “And he shall nip off … and cause it to ascend in fumes … and the blood thereof shall be wrung out. Is it possible to say that after he has burnt it, he should squeeze the blood out? But [the order of the wording] is to teach us that just as the burning of the head is to be done separately [as is indicated here in the verse, and he shall nip off its head, and cause it to ascend in fumes], and that of the body is to be done separately [as is stated further on in Verse 17: and he shall cleave it … and cause it to ascend in fumes], so also the nipping off has to be done in this way, the head separately and the body separately. The plain meaning of the verse, however, is that the wording is to be inverted: and he shall nip off and cause it to ascend in fumes, and before the burning its blood shall have been wrung out.” This is Rashi’s language.
Now it is impossible to say [that the order of the verse can be explained to mean] that he should nip off its head and burn it, and afterwards wring the blood of the body on the wall of the altar and then burn the body, since no limbs of any offering may ever be burnt [on the altar] before the sprinkling of the blood, the principle for it is the blood that maketh atonement by reason of the life, and the wringing of the blood can nonetheless be done subsequently because it refers to the body’s blood. Rashi, however, was compelled to invert the word-order because this suggested explanation is impossible, as explained by Ramban. applying to all offerings. Therefore the Rabbis interpreted the verse [to mean] that Scripture intended only to liken the nipping off to the burning, so that in both cases the head should be treated by itself and the body by itself. The plain sense of the verse, however, is that “he should nip off its head in order to burn it on the altar,” thus teaching that the nipping off should be done in order to burn the head [separately, and not dispose of it otherwise], just as he will burn the body, concerning which He said, and the priest shall cause it to ascend in fumes, for such is Scriptures’ way of speaking about all offerings, as I have explained in connection with the severance into pieces of the burnt-offering. However, Scripture states here, and the priest shall cause it to ascend in fumes, and did not say “and he shall cause all to ascend” [as it said above in Verse 9, in the case of the burnt-offering of the herd], because [here in the case of the burnt-offering of the fowl] the burning thereof was done in two separate stages: first he burnt the head, and then he removed the crop [from the body], and cleft it by the wings, and then he burnt the body, as we have been taught in Tractate Zebachim.

ומלק, our sages explain exactly how this was done. (compare Chulin 8) They base their exegesis on the wording of ומלק את ראשו instead of ומלק אותו, which would have been the parallel of the words ושחט אותו, which the Torah uses to describe the killing of the four-legged sacrificial animal. Dunash [Dunash ben Labrat, a tenth century grammarian born in Fez, disciple of Rabbi Saadyah Gaon. Ed.] explains that a further proof of the correctness of our sages’ exegesis is that they had been eye witnesses of the manner in which the birds’ throat and spine would be snipped with the fingernail of the priest, etc.

ונמצה, this term is appropriate when speaking of something soft, as we know from Isaiah 51,17 את קובעת כוס התרעלה שתית מצית, “who have drunks the dregs of the cup,” or Psalms 75,9 אך שמריה ימצו, “Only its dregs will they drain.”

ונמצה דמו על קיר המזבח, “and its blood shall be drained out on the side of the altar.” Seeing we speak about a minute amount of blood, no special bowl had been used in first collecting it. Had it first been collected in a bowl there would not have been enough left over to sprinkle it, hence it was squeezed out against the side of the altar.