Yoma, Chapter Five, Mishnah Four
In this mishnah the high priest slaughters the goat and then sprinkle the blood of the goat inside the Holy of Holies and the blood of both the goat and the bull on the curtain outside the Holy of Holies.
1) They would bring him the goat. He would slay it and receive its blood in a bowl.
2) He entered [again] into the place where he had entered, and stood [again] on the place on which he had stood, and sprinkled once upwards and seven times downwards, and he wouldnt intend to sprinkle either upwards or downwards but rather like one who cracks a whip. And thus would he count: one, one and one, one and two, one and three, one and four, one and five, one and six, one and seven. Then he would go out and place it on the second [golden] stand in the Hekhal.
a) Rabbi Judah said: there was only one golden stand there.
3) He would take the blood of the bull and put down the blood of the goat, and sprinkle from it upon the curtains facing the Ark outside, once upwards, seven times downward, aiming to sprinkle neither upwards nor downwards, and he wouldnt intend to sprinkle either upwards or downwards but rather like one who cracks a whip. Thus would he count [as above].
a) Then he would take the blood of the goat, and put down the blood of the bull, and sprinkle from it upon the curtain facing the ark outside once upwards, seven times downwards [as above].
4) Then he would pour the blood of the bull into the blood of the goat emptying the full vessel into the empty one.
Section one: This is the goat which was determined by lot to be For Hashem as we read in 4:2 above. He slaughters it and receives its blood in a bowl.
Section two: He then brings the blood of the goat into the Holy of Holies and does the same type of sprinkling that he did with the bulls blood (see 5:3). This is mentioned in Leviticus 16:15. There is a debate in the mishnah between the first opinion and Rabbi Judah concerning how many special stands were prepared to hold bowls with blood.
Section three: The beginning of this section goes according to Rabbi Judah who holds that there was only one special stand. He says that first the high priest picks up the bowl with the bulls blood in it and then puts down the bowl with the goats blood. According to the first opinion, the high priest first puts down the goats blood on its own stand and then picks up the bulls blood.
Section three: The next task at hand is to sprinkle blood on the curtain, opposite the place where the ark is (or used to be) in the Holy of Holies. He does this while standing in the Hekhal, outside of the Holy of Holies. This is referred to in the second half of Leviticus 16:16. The same order is followed; first he sprinkles the bulls blood and then he sprinkles the goats blood.
Section four: Leviticus 16:18 states, he shall take some of the blood of the bull and of the goat and apply it to each of the horns of the altar. The rabbis understand this to mean that he mixes the two bloods together. Therefore he first pours the bulls blood into the bowl with the goats blood and then pours the whole mixture back into the other bowl to ensure that they are mixed well.