632. Jewish and Non-Jewish Business Partners
Shabbos 6:17
Let’s say that a Jew entered into a business partnership with a non-Jew. If a condition was made at the outset, then the profits generated on Shabbos, whether they are great or small, may be assigned exclusively to the non-Jewish partner in exchange for which the profits of a different day may be assigned exclusively to the Jewish partner. If such a condition was not stipulated at the outset, then when the partners divide their profits, the non-Jewish partner should take all the profits from Shabbos for himself and the rest of the profits should be divided evenly between them. The non-Jewish partner does not have to compensate the Jewish partner in any way unless such a condition was made in advance. The same rules would apply if they rent a field as partners.
Shabbos 6:18
If a condition was not made and, when they went to divide the profits, the profits generated on Shabbos were not distinguishable from the rest of the profits, it seems that the non-Jewish partner should take one-seventh of the profits for himself and the rest should be divided evenly between them. If a Jew gives a non-Jew money to invest, the partners may divide the profits equally between then even though the non-Jewish partner may have engaged in business transactions with the money on Shabbos. All of the Geonim agree on this.