[If] his wife lost the baby, he is not a nazir. R’ Shimon says: He should say: “If it was [a] viable [child], I am a nazir by [previous] obligation, but if not, I am a nazir voluntarily.” [If] she again gave birth, he is a nazir. R’ Shimon says: He should say: “If the first was viable, the first [nezirus] was obligatory, and this one is voluntary; but if not, the first [nezirus] was voluntary, and this one is obligatory.”