משנה אויף במדבר 30:7

One who said, “Behold, I am a nazirite”, and his friend overheard and said “I too,” [and another one said] “I too”, all are nazirites. If the first one is released [from his vow], all are released. If the last one is released, he alone is released, and the others remain bound [by their vows]. If he said, “Behold, I am a nazirite”, and his companion overheard and said, “My mouth shall be as his mouth and my hair as his hair”, he becomes a nazirite. [If he said,] “Behold, I am a nazirite,” and his wife overheard and said, “I too,” he can annul her vow, but his own remains binding. [If a woman says,] “Behold, I am a nazirite”, and her husband overhears and adds, “I too,” he cannot annul her vow.