Commentary for Leviticus 5:9

והזה מדם החטאת AND HE SHALL SPRINKLE OF THE BLOOD OF THE SIN-OFFERING [… AND THE REMAINDER OF THE BLOOD SHALL BE WRUNG OUT] — In the case of a burnt-offering of a fowl Scripture requires only the wringing out of the blood (Leviticus 1:15), whilst in the case of the sin-offering it requires sprinkling and wringing out: standing quite near to the altar, he grasps the nape and makes the blood spurt out and thus the blood spurts forth in a jet and goes in the direction of the altar (cf. Zevachim 64b).

והזה מדם החטאת; he takes hold of the body of the bird and sprinkles from a distance, squeezing out the rest of the blood; if the offering is a total offering, there is no sprinkling of the blood; all of it is simply squeezed out. (Leviticus 1,15)

For its sake. This was explained above (Rashi 4:24) regarding the sin-offering of a leader. Rashi repeats it [here] because it is dealing with bird sinoffering and above it is dealing with an animal sin-offering, and [one cannot learn from the other because] they have dissimilar aspects. Therefore, he repeated the explanation here.

והנשאר בדם ימצה, “and the remainder of the blood shall be drained out;” the priest walks around the side of the altar and squeezes the bird against the wall of the altar so that the blood drains by itself. The word is spelled here with the letter א at the end [not in any of the editions of the chumash or training Torah scrolls at my disposal. According to one commentary I have seen the author had the same spelling in front of him as do we, but he means that the vowel tzeyre instead of the vowel segol the result is that the meaning is as if the letter ה had been written instead of the letter א. Ed.] It suggested that the blood ends up the same way as does the blood which had been sprinkled, namely at the base of the altar.

חטאת הוא IT IS A SIN-OFFERING — These apparently redundant words intimate: if the sprinkling and wringing of the blood are done for the purpose of (i.e. having in mind that it is) a sin-offering it is valid; if it is not done for this purpose (i.‎e. that the officiating priest has another sacrifice in mind) it is invalid (cf. Sifra, Vayikra Dibbura d'Chovah, Chapter 18 9 and Rashi on Leviticus 4:24).