פּירוש אויף שמות 24:6

ויקח משה חצי הדם AND MOSES TOOK THE HALF OF THE BLOOD — Who divided it into halves? An angel came down and divided it (Leviticus Rabbah 6:5).

וישם באגנות, “he placed it in basins.” Rashi explains that we learn from this verse that it requires three steps to convert to Judaism fully: circumcision, immersion in a ritual bath, and the sprinkling of blood. And when the Talmud in tractate Yevamot folio 46 stated that our forefathers were circumcised but did not immerse themselves in a ritual bath, we must say that this refers to our forefathers Avraham, Yitzchok, and Yaakov. [How could they have done so since the Torah had not been given in their time as yet? Ed.]

AND MOSES TOOK HALF OF THE BLOOD AND HE PLACED IT ‘BA’AGANOTH.’ These are vessels made unlike the shape of the regular basins of the altar. Hence Scripture states that half of the blood of the sacrifices which Moses intended to sprinkle on the people, he put into these vessels, and the other half he sprinkled upon the altar from the regular basins in which he had received the blood, as is the customary way with all offerings. But Rabbi Abraham ibn Ezra said that ba’aganoth served for both halves, [and thus the word signifies the regular basins of the altar]. Such is also the opinion of Onkelos, who translated ba’aganoth as b’mizr’kaya [a term referring to the regular basins].

באגנת IN BASONS — There were two basons, one for holding the half of the blood of the burnt offering and the other for holding the half of the blood of the peace offerings, in order to sprinkle it (both bloods) on the people. From here have our Rabbis inferred (Keritot 9a) that our ancestors entered into the covenant with God by means of circumcision, immersion and sprinkling of blood — and although immersion is not mentioned in this paragraph it must have taken place, for no sprinkling is effective without immersion preceding it (cf. Tosafot Yevamot 46b ד"ה דאין הזאה בלא טבילה).‎