Someone who vowed to be a nazir, and [when] he went to bring his animal, he found that it had been stolen —- if he declared himself a nazir before the animal had been stolen, he is a nazir; if he declared himself a nazir after the animal had been stolen, he is not a nazir. And this error was made by Nachum the Mede: When [a group of] nezirim came up from the Diaspora and found the Temple destroyed, Nachum the Mede said to them: “If you had known that the Temple would be destroyed, would you have vowed to be nezirim?” They answered him: “No!” So Nachum the Mede released them. But when the matter came before the Sages, they said to him: “Anyone who declared himself a nazir before the Temple was destroyed is a nazir; after the Temple was destroyed, he is not a nazir.”