R. Hanan bar Pazzi opened [his discourse] with the verse in [the context of] the parashah of the [red] heifer, which contains seven [references to] seven things: seven [references to] heifers, seven [items for] burning, seven sprinklings, seven [instances of] laundering [clothes], seven [ways of becoming] unclean, seven [people or things who become] clean, and seven priests.
If someone should say to you, ‘[The number of priests] is lacking,’ say to him, ‘Moses was [included] in the total, where it is stated (in Numb. 19:1-2), “Then the Lord spoke unto Moses and unto Aaron, saying, ‘This is the statute of the Torah.’”’”