655. Non-Jews Working for Themselves on Shabbos

90:20 If a non-Jew delivers grain to a Jew as payment for money he owes him, and the Jew gives him the key to his storehouse so that the non-Jew measures out the proper amount of grain and leaves it there, this is permitted on Shabbos. The non-Jew is considered to be working for himself since the grain does not belong to the Jew until after it's been measured out. The Jew is allowed to be present while the non-Jew measures out the grain to ensure that he receives what he is due so long as he does not discuss the transaction. However, if they brought the Jew his own grain, he may not instruct them to unload it from the wagons into his storehouse. Even if they want to do this, the Jew must object.

90:21 If a non-Jew is making cheese from his own milk on Shabbos, a Jew is allowed to supervise the milking and the cheese-making so that the cheese will be permitted to Jews and he can buy it after Shabbos. Even though the non-Jew intends to make this cheese to sell to the Jew, it is permitted because the cheese is owned by the non-Jew and he is making it for his own benefit. The Jew is even allowed to instruct the non-Jew to make it, even on Shabbos itself. This is because a Jew may tell a non-Jew to do his own work, even though the Jew will benefit from it.