hair cutting was a religious duty: nazirites (as stated in ), those afflicted with skin disease (, metzora, as stated in ), and the Levites. Citing the Mishnah, the Gemara taught that if any of them cut their hair without a razor, or left behind two hairs, their act was invalid. Rabbi Jose the Galilean cited the use of "second" in to rule that bulls brought for sacrifices had to be no more than two years old. But the Sages ruled that bulls could be as many as three years old, and Rabbi Meir ruled that even those that are four or five years old were valid, but old animals were not brought out of respect. Reading , "And the Levites shall be Mine," a Midrash taught that wherever Scripture says "to Me" or "Mine," it refers to something that shall never cease either in this world or in the World to Come. The Mishnah deduced from that before Moses set up the Tabernacle, the firstborn performed sacrifices, but after Moses set up the Tabernacle, priests performed the sacrifices. Rabbi Judan considered God's five mentions of "Israel" in to demonstrate how much God loves Israel. The Jerusalem Talmud reported that Rabbi Tanhuma in the name of Rabbi Lazar deduced from that the Levites' singing made atonement for the Israelites. A Baraita taught that the priests did the sacrificial service, the Levites sang on the platform while the priests offered the sacrifices, and the Israelites served as emissaries of the entire people when they attended the sacrifices. And another Baraita reported that Rabbi Simeon ben Eleazar taught that priests, Levites, Israelites, and song were all essential for an offering. Rabbi Avin said in the name of Rabbi Eleazar that provided support for this when it says, "And all the congregation prostrated themselves," these being the Israelites; "and the singers sang," these being the Levites; "and the trumpeters sounded," these being the priests; and the conclusion of the verse, "all this continued until the burnt-offering was finished," demonstrated that all were essential to complete the offering. Rabbi Tanhuma said in the name of Rabbi Lazar that one may learn this from "And I have given the Levites," these being the Levites; "to do the service of the children of Israel in the tent of meeting," these being the priests; "and to make atonement for the children of Israel," this being brought about