[If] one divorced his wife and said to her: “You are permitted to every man, except So-and-so” —- R' Eliezer permits [her]; the Sages, however, prohibit [her]. What shall he do? He must take it from her and give it to her again, and say to her: “You are permitted to every man.” If he wrote it inside it, although he subsequently erased it, it is void.