Talmud for Gittin 5:9
מַשְׁאֶלֶת אִשָּׁה לַחֲבֶרְתָּהּ הַחֲשׁוּדָה עַל הַשְּׁבִיעִית, נָפָה וּכְבָרָה וְרֵחַיִם וְתַנּוּר, אֲבָל לֹא תָבֹר וְלֹא תִטְחַן עִמָּהּ. אֵשֶׁת חָבֵר מַשְׁאֶלֶת לְאֵשֶׁת עַם הָאָרֶץ, נָפָה וּכְבָרָה, וּבוֹרֶרֶת וְטוֹחֶנֶת וּמַרְקֶדֶת עִמָּהּ, אֲבָל מִשֶּׁתַּטִּיל הַמַּיִם, לֹא תִגַּע עִמָּהּ, לְפִי שֶׁאֵין מַחֲזִיקִין יְדֵי עוֹבְרֵי עֲבֵרָה. וְכֻלָּן לֹא אָמְרוּ אֶלָּא מִפְּנֵי דַרְכֵי שָׁלוֹם. וּמַחֲזִיקִין יְדֵי גוֹיִם בַּשְּׁבִיעִית, אֲבָל לֹא יְדֵי יִשְׂרָאֵל, וְשׁוֹאֲלִין בִּשְׁלוֹמָן, מִפְּנֵי דַרְכֵי שָׁלוֹם:
A woman may lend her neighbor who is suspect of shevi'ith [i.e., of keeping the fruits of the sabbatical year and of secreting them from (the time of their required) removal on: a sifter, a sieve, a mill, and an oven. But she may not sieve or grind with her [to assist her, it being forbidden to directly assist transgressors in their act of transgression.] The wife of a chaver (a Torah scholar) may lend a sifter or a sieve to the wife of an ignorant man, and she may sieve and grind and sift with her, [for the majority of the ignorant tithe]; but when she puts water [on the dough], she may not touch it with her, [for when she rolls it, it becomes subject to challah, and it becomes unclean by contact with unclean vessels, the yeast having become susceptible to uncleanliness (by the addition of the water), and she helps her to roll; and it is forbidden to impart uncleanliness to challah.] And all were stated only to foster peace. [They allowed them to lend them vessels and to help them (not at the time of the transgression itself) only to foster peace.] And the hands of gentiles may be strengthened [i.e., it is permitted to wish them success (when they work their fields on the sabbatical year)]; but not the hands of Jews (who perform such labor). And they (the gentiles) are greeted [on all days, even on their festivals, even though they are thereby graced with the name of Heaven, "Shalom" (Peace) being one of the names of the Holy One Blessed be He], to foster peace.