[If one says:] “I am a nazir, and it is [an obligation] upon me [to provide for] a nazir to shave [his head],” and his friend heard [him] and said, “And I, and it is [an obligation] upon me [to provide for] a nazir to shave [his head]” —- if they are clever, they [provide for] each other [to] shave, and if not, they [must provide for] other nezirim [to] shave.