Gitin7: 1
מִי שֶׁאֲחָזוֹ קֻרְדְּיָקוֹס וְאָמַר: ,,כִּתְבוּ גֵט לְאִשְׁתִּי” — לֹא אָמַר כְּלוּם. אָמַר: ,,כִּתְבוּ גֵט לְאִשְׁתִּי” וַאֲחָזוֹ קֻרְדְּיָקוֹס, וְחָזַר וְאָמַר: ,,אַל תִּכְתְּבוּ” — אֵין דְּבָרָיו הָאַחֲרוֹנִים כְּלוּם.  נִשְׁתַּתַּק, וְאָמְרוּ לוֹ: ,,נִכְתֹּב גֵּט לְאִשְׁתְּךָ?” וְהִרְכִּין בְּרֹאשׁוֹ — בּוֹדְקִין אוֹתוֹ שְׁלֹשָׁה פְּעָמִים: אִם אָמַר עַל ,,לָאו” ,,לָאו”, וְעַל ,,הֵן” ,,הֵן” — הֲרֵי אֵלּוּ יִכְתְּבוּ וְיִתְּנוּ.
One who was seized by delirium and said: “Write a get for my wife,” did not say anything. [If] he said: “Write a get for my wife,” and was seized by delirium, and he then said: “Do not write it,” his latter words are worthless.  [If one] became mute, and they said to him: “Shall we write a get for your wife?” and he nodded with his head, they test him three times. If he said “no” for a “no,” and “yes” for a “yes,” they may write and give [it].
Gitin7: 2
אָמְרוּ לוֹ: ,,נִכְתֹּב גֵּט לְאִשְׁתְּךָ?” וְאָמַר לָהֶם: ,,כְּתֹבוּ”; אָמְרוּ לַסּוֹפֵר, וְכָתַב, וְלָעֵדִים, וְחָתָמוּ; אַף עַל פִּי שֶׁכְּתָבוּהוּ וַחֲתָמוּהוּ וּנְתָנוּהוּ לוֹ, וְחָזַר וּנְתָנוֹ לָהּ — הֲרֵי הַגֵּט בָּטֵל, עַד שֶׁיֹּאמַר לַסּוֹפֵר: ,,כְּתֹב”, וְלָעֵדִים: ,,חֲתֹמוּ”.
[If] they said to him: “Shall we write a get for your wife?” and he said to them: “Write,” [and] they told a scribe, and he wrote; or witnesses, and they signed, although they wrote it, signed it, and gave it to him, and he, in turn, gave it to her, the get is void unless he says to the scribe: “Write,” and to the witnesses: “Sign.”