101 Gittin 2/2-5

(2) If it was written in the daytime and signed in the daytime, [or written] at night and signed at night, [or written] at night, but signed in the daytime, it is valid. If it was written in the daytime, but signed at night, it is invalid. But Rabbi Shimon declares it valid, as Rabbi Shimon would say, "All documents written during the daytime and signed at night are invalid, except for bills of divorce."

(3) One may write [a bill of divorce] with any [material]: with ink, with paint, with red paint, with gum, or with vitriol black, and with every other permanent material. One may not write [it] with a drink, nor with fruit juice, nor with any impermanent material. One may write [it] on anything: on an olive leaf; on a cow's horn, but he must give her the cow; on the hand of a slave, but he must give her the slave. Rabbi Yossi HaGelili says, "One may not write on anything that has the spirit of life, nor on foods."

(4) One may not write [it] on anything that is attached to the ground. [If] one wrote it on something attached, [and] he detached it and signed it and gave it to her, it is valid. Rabbi Yehudah declares it invalid, until its writing and its signing be on something that is detached [from the ground]. Rabbi Yehudah ben Beteirah says, "One may not write it erased paper, nor on hide prepared for writing, because it can be [easily] forged." But the Sages declare it valid.

(5) All are qualified to write a bill of divorce, even a deaf-mute, a shoteh and a minor. A woman may write her own bill of divorce, and the husband his receipt [for the amount of the ketubah [monetary settlement payable to a married woman upon divorce or the death of her husband] he has paid her], because the affirmation of legal documents depends solely on the signers. All are valid [agents] to bring a bill of divorce, except for a deaf-mute, an shoteh, a minor, a blind person, and a non-Jew.