625. When a Non-Jew Performs Labor for Himself

Shabbos 6:3

If a non-Jew lit a light for his own use, a Jew may also do things by its light. If the non-Jew lit the light for a Jew, it is prohibited to use its light. Similarly, if a non-Jew set up a ramp to disembark from a ship, a Jew may disembark after him; if he set it for the Jew, it is prohibited. If a non-Jew filled a trench with water so his animal could drink, a Jew may let his animal drink afterwards; if the non-Jew did so for the Jew, it is prohibited. If a non-Jew gathered grass to feed his animal, a Jew may bring his animal to eat some as long as the non-Jew doesn’t know him. If he knows the Jew, it is prohibited out of concern that he may bring more for the Jew. Similarly, whenever there is a chance that a non-Jew will perform more labor, a Jew may not benefit unless the non-Jew does not know him.

Shabbos 6:4                                                                                                   

If there is no chance that the non-Jew will increase or decrease his work for the Jew’s benefit, such as lighting a light or setting up a ramp, then if the non-Jew does these things for himself, a Jew is permitted to benefit from them on Shabbos after the non-Jew, even if the non-Jew knows him. If a light was lit on Shabbos for a group of Jews and non-Jews, then if most of the group are Jewish, it is prohibited to use the light because the one who lit it does so for the majority. Therefore, if the majority are non-Jews, it is permitted to use the light. If the number of Jews and non-Jews in the group are equal, it is prohibited. If a fire breaks out on the Sabbath and a non-Jew comes to put it out, we may not tell him to douse it. On the other hand, we don’t tell him not to put it out either because it’s not our responsibility to make him refrain from labor. This principle applies in all similar circumstances.