אבן העזר קמ״חEven HaEzer 148

Se’if 1א׳

מִי שֶׁכָּתַב לְגָרֵשׁ אֶת אִשְׁתּוֹ, וְנִמְלַךְ וְלֹא גֵּרְשָׁהּ, וְנִתְיַחֵד עִמָּהּ אַחַר שֶׁכְּתָבוֹ, לֹא יְגָרְשֶׁנָּהּ בְּאוֹתוֹ הַגֵּט פַּעַם אַחֶרֶת כְּשֶׁיִּרְצֶה לְגָרְשָׁהּ. וְאִם גֵּרְשָׁהּ בְּאוֹתוֹ הַגֵּט הַיָּשָׁן, הֲרֵי זוֹ מְגֹרֶשֶׁת וְתִנָּשֵׂא בּוֹ לְכַתְּחִלָּה, שֶׁהֲרֵי נִכְתַּב לִשְׁמָהּ וַהֲרֵי נָתַן לָהּ עַתָּה בְּעֵדִים כְּהִלְכָתוֹ. וְלָמָּה לֹא יְגָרְשֶׁנָּה בּוֹ לְכַתְּחִלָּה, גְּזֵרָה שֶׁמָּא יֹאמְרוּ גִּטָּהּ קוֹדֵם לִבְנָהּ. וְיֵשׁ אוֹמְרִים דְּהָנֵי מִלֵּי כְּשֶׁהַגֵּט בְּיַד הַבַּעַל וּמְסָרוֹ מִיָּדוֹ לְיָדָהּ, אֲבָל אִם שְׁלָחוֹ לָהּ עַל יְדֵי שָׁלִיחַ, וְנִתְיַחֵד עִמָּהּ אַחַר שֶׁנְּתָנוֹ לְיַד הַשָּׁלִיחַ, וּנְתָנוֹ לָהּ הַשָּׁלִיחַ, לֹא תִּנָּשֵׂא בּוֹ, וְאִם נִשֵּׂאת, לֹא תֵּצֵא:

If a man wrote [a get (that is, a divorce document)] to his wife, and then he decided not to divorce her, and then he was secluded with her after he wrote it, he may not divorce her with that get another time if he decicdes to divorce her. And if he divorced her with this get yashan (that is, this get that was written before he was secluded with her), then she is divorced and may remarry, for this get was written for her and it was given with witnesses, as the law mandates. And why may he not divorce her with [with a get yashan] at the outset? [Because] maybe [she will become pregnant from the husband during that time of seclusion] and people will say that the get was delivered before she became pregnant. There are those that say that the aforementioned law [that if a get yashan was used, then she is permitted to remarry] only applies if the man delivered the get directly. However, if he sent it to her through an agent, and then he secluded himself with her after he gave the get to the agent and after the get was delivered, then she may not get married with the get [as evidence that she was legally divorced] but, if she did remarry [with it] she does not need to leave [the new husband].

Se’if 2ב׳

כָּל הַמְגָרֵשׁ עַל תְּנַאי, בֵּין שֶׁאָמַר: מֵעַכְשָׁו, בֵּין שֶׁאָמַר: אִם יִהְיֶה וְאִם לֹא יִהְיֶה, הֲרֵי זֶה לֹא יִתְיַחֵד עִמָּהּ כָּל זְמַן שֶׁלֹּא נִתְקַיֵּם הַתְּנַאי, אֶלָּא בִּפְנֵי עֵד, אֲפִלּוּ עֶבֶד וַאֲפִלּוּ שִׁפְחָה, וּבְיוֹצֵא וְנִכְנָס סָגֵי, חוּץ מִשִּׁפְחָתָהּ אוֹ בְּנָהּ הַקָּטָן, מִפְּנֵי שֶׁאֵינָהּ בּוֹשָׁה לְשַׁמֵּשׁ בִּפְנֵיהֶם. וְהַדָּבָר יָדוּעַ שֶׁאִם נִתְיַחֵד עִמָּהּ בִּפְנֵי שְׁנֵי עֵדִים כְּאֶחָד, וְרָאָה הוּא וְהִיא אוֹתָם, אֲפִלּוּ נִתְקַיֵּם הַתְּנַאי אַחַר כָּךְ, הֲרֵי זוֹ סְפֵק מְגֹרֶשֶׁת, שֶׁמָּא בְּעָלָהּ וּבִטֵּל הַגֵּט, וְיִתְבָּאֵר בְּסִימָן שֶׁאַחַר זֶה:

Anyone who divorces on condition, whether he says, "[You will be divorced] from now..." whether he says, "If it will be... and if it won't be..." he cannot be in seclusion with her as long as the condition has not been fulfilled, unless there is a witness present, even [if the witness is] a slave or a maidservant, and it is enough for [the witness] to come in an out [to be a random presence], the exception being one of her maidservants, or her small son, for she would not be embarrassed to have intercourse in their presence. And it is known that if he was in seclusion with her with two witnesses who were together, and they saw him and her, even if the conditions are fulfilled afterward, it is a doubt-divorce, for perhaps they had intercourse and the bill of divorce was made null and void, and it will be explained in the next siman.