פירוש על גיטין 2:2

בלילה ונחתם ביום כשר – since the daytime goes after the [previous] night, and this is not in advance/early.

Introduction It is necessary to write the date inside a get. Our mishnah deals with a cases where the get was written on one day but signed on the night that follows, which is considered the following day according to the Jewish way of reckoning days and nights. In this case, the get’s date will not match the date upon which it is finalized.

ביום ונחתם בלילה פסול – since it is early. And the Sages instituted the time in Jewish bills of divorce, decreed, less a person would be married with his sister’s daughter (niece}, and she will commit an offense against him, and he has compassion upon her that she not be strangled to death, and he gives her a Jewish bill of divorce without the time included, and when they testify against her in the Jewish court, she takes out her Jewish bill of divorce and states that she was a divorcee and was a free (literally, “open”) woman at that time.

If [a get was] written by day and signed on the [same] day, written by night and signed on the [same] night, written by night and signed on the day [following], it is valid. In all of these cases the get is valid since it was written and signed on the same day. Since the day follows the night in Jewish counting of days, if it was written at night and signed the following day, this still counts as being written and signed on the same day.

ור"ש מכשיר – (a Jewish bill of divorce written in the daytime and signed at night), for Rabbi Shimon thinks (i.e., “holds”) that the Sages established [putting] the time in the Jewish bill of divorce because of the usufruct [involved], for if the time would not be [stated] in the Jewish bill of divorce, the husband would sell the usufruct (the wife’s estate of which the husband has fruition without responsibility for loss or deterioration – while married] of his wife after the divorce, and when she would claim against him in court, he would claim that he sold it prior to the divorce. And Rabbi Shimon validates this when it [the Jewish bill of divorce] was written during the day time and signed at night, even though it is in advance. For he holds that from the time that he desired to divorce her even though he had not [yet] divorced her, from then on, the husband does not have [access to] the usufruct, but the Halakha is not according to Rabbi Shimon.

If it was written by day and signed on the night [following], it is invalid. Rabbi Shimon validates it, for Rabbi Shimon used to say that all documents written by day and signed on the [following] night are invalid except bills of divorce. However, if it was written by day and then later signed that night, the date written in the get does not match the actual date on which it was signed. The reason why documents must be written and signed on the same day is that documents can be used to collect collateral. A debt document creates a lien on another person’s property. For instance, if Reuven borrows 1,000 dollars from Shimon on the first of the month of Av, Shimon now has a lien on all the property that Reuven owned on that date. If Reuven subsequently gives or sells property to a third party and then defaults on his loan, Shimon may collect from the third party. However, Shimon’s lien takes priority only over other debts created after Shimon loaned the money. For this reason, documents whose dates precede their finalization, done in their signing, are invalid, lest someone try to defraud a third party. Since all other documents whose dates precede their finalization are invalid, divorce documents are as well. According to Rabbi Shimon, money is never collected based on the date written in the get. A woman collects her ketubah based on the date written in the ketubah. Therefore, the get which was written during the day but only signed at night is valid. Even though other documents whose date precedes their signing are invalid, gittin are valid.