משנה על עבודה זרה 4:1

A woman may lend to her neighbor who is suspect of transgressing the laws of the sabbatical year, a sifter, a sieve, a hand-mill, or an oven. But she may not sift or grind with her. The wife of a haver may lend to the wife of an am haaretz a sifter and a sieve and may even sift, grind, or sift flour with her. But once she poured water [over the flour], she may not touch [it] with her, for one may not aid those who commit a transgression. And all these things were only allowed in the interests of peace. They may offer encouragement to Gentiles during the sabbatical year, but not to Jews. In the interests of peace, one may also offer greetings to Gentiles.