Erchin9: 3
הַמּוֹכֵר בַּיִת בְּבָתֵּי עָרֵי חוֹמָה, הֲרֵי זֶה גּוֹאֵל מִיָּד, וְגוֹאֵל כָּל־שְׁנֵים עָשָׂר חֹדֶשׁ. הֲרֵי זֶה כְּמִין רִבִּית, וְאֵינָהּ רִבִּית. מֵת הַמּוֹכֵר, יִגְאֹל בְּנוֹ. מֵת הַלּוֹקֵחַ, יִגְאֹל מִיַּד בְּנוֹ. אֵינוֹ מוֹנֶה לוֹ שָׁנָה, אֶלָּא מִשָּׁעָה שֶׁמָּכַר לוֹ, שֶׁנֶּאֱמַר: ,,עַד מְלֹאת־לוֹ שָׁנָה תְמִימָה.“ וּכְשֶׁהוּא אוֹמֵר: ,,תְמִימָה“ — לְהָבִיא חֹדֶשׁ הָעִבּוּר. רַבִּי אוֹמֵר: יִתֶּן־לוֹ שָׁנָה וְעִבּוּרָהּ.
[If] one sells a house of the houses of walled cities, he may redeem [it] immediately, and he may redeem [it] all twelve months. This is like a kind of interest, but it is not interest. Should the seller die, his son may redeem [it]. Should the buyer die, he may redeem [it] from his son. He counts the year for it only from the time he sold [it] to him; as it says: Until a full year has elapsed for him (Lev. 25:30). When [Scripture] says: full, [it comes] to include the intercalary month. Rabbi says: He must give him a year and its intercalary [days].
Erchin9: 4
הִגִּיעַ יוֹם שְׁנֵים עָשָׂר חֹדֶשׁ וְלֹא נִגְאַל, הָיָה חָלוּט לוֹ. אֶחָד הַלּוֹקֵחַ וְאֶחָד שֶׁנִּתַּן־לוֹ מַתָּנָה; שֶׁנֶּאֱמַר: ,,לַצְּמִיתֻת.“ בָּרִאשׁוֹנָה הָיָה נִטְמָן יוֹם שְׁנֵים עָשָׂר חֹדֶשׁ, שֶׁיְּהֵא חָלוּט לוֹ. הִתְקִין הִלֵּל הַזָּקֵן, שֶׁיְּהֵא חוֹלֵשׁ אֶת־מָעוֹתָיו בַּלִּשְׁכָּה, וִיהֵא שׁוֹבֵר אֶת־הַדֶּלֶת וְנִכְנָס. אֵימָתַי שֶׁיִּרְצֶה הַלָּה, יָבֹא וְיִטֹּל אֶת־מָעוֹתָיו.
[If] the [final] day of the twelve months arrived and it was not redeemed, it would become permanently his. [This applies] both to the buyer and the recipient of a gift; as it says: In perpetuity (Lev. 25:30). Originally, he would hide on the [final] day of the twelve months so that it should become permanently his. Hillel the Elder enacted that he should deposit his money in the chamber, and break [down] the door and enter. Whenever the other one so desires, he may come and take his money.