Gittin 8:10-9:1

Gittin 8:10

A get keireiach is one that has more places to sign than it has signatures. (Such a get is invalid out of concern that the husband may have instructed witnesses to sign who did not do so.) According to Ben Nanas, anyone can complete a get keireiach (even people normally disqualified from serving as witnesses, such as relatives, servants and sinners); Rabbi Akiva says that only relatives who can serve as witnesses in other circumstances can complete a get keireiach (but not those others permitted by Ben Nanas).

Gittin 9:1

Let’s say that a man divorces his wife specifying that she can marry anyone else except for one particular person. Rabbi Eliezer says that this is permitted (and the divorce is valid) but the Sages prohibit it (and do not consider the divorce to be finalized). In such a case, the man should take the get and hand it to her again, this time specifying that she is free to marry anyone else. If he wrote the restriction against marrying a certain person in the get, even if he subsequently erased it, the get is invalid.