Yerushalmi Eruvin 4:3 ירושלמי עירובין ד׳:ג׳

MISHNAH: If somebody left with permission⁷If a border town is attacked by marauders, it may ask the nearby towns for armed help. when they told him that the deed already had been done he has 2’000 cubits in each direction. If this reached him inside the Sabbath domain⁸If at the moment when the help is no longer needed the person was no more than 1’999 cubits from the border of the Sabbath domain of his home town, he may reach this domain and, since he left with permission, walks all the way to his house. If the built-up area was within 2’000 cubits the statement is unnecessary since any built-up area is counted as 4 cubits. it is as if he never left, for all those who leave to save may return to their place.

HALAKHAH: Paragraph. “If somebody left with permission,” etc. For otherwise what would we say? That he should be treated like somebody who left by compulsion and he should have only four cubits. Therefore it was necessary to say, “he has 2’000 cubits in each direction.” Rav Ḥuna says, only if four cubits each intersect with the domain of Tiberias and with the domain of Magdala⁶¹The distance from the Sabbath border of Tiberias to that of Magdala was less than 2’000 cubits. Therefore if somebody from Tiberias was informed just inside the border of the Sabbath domain of Magdala that he was no longer needed, he might return 2’000 cubits in the direction of Tiberias and end up 4 cubits inside the Sabbath domain of that city. Then he would be as if he had never left; cf. Note 8; Babli 44b.. Rebbi Ḥuna in the name of Rav Ada bar Aḥawa, Rebbi La in the name of Rebbi Simeon ben Laqish. Even if he went to Magdala and returned he is as if he had not left⁶²Being at Magdala with permission lets him go back 2’000 cubits outside its Sabbath domain towards Tiberias. Since then he is inside the Sabbath domain of Tiberias it is as if he never left, even if he was informed only inside the town of Magdala itself.. Rebbi Joshua the Southerner asked: So far if he left in error⁶³Mishnah 3 only refers to the case that he genuinely believed that his services were urgently needed.. Even if he left intentionally? Rebbi Phineas said, the Mishnah says so: “for all those who leave to save may return to their place.⁶⁴The inclusion of “all” means that the motives of those coming to help cannot be investigated.”

⁶⁵Babli 45a, Tosephta 3:5–6. It was stated: “Gentiles who attack villages near the border to rob, even straw or even wood, one goes out against them armed and brings the weapon back to its place. If they attack interior villages one goes out only if it is a matter of life⁶⁶If they come to kill or kidnap.. In earlier times they stored the weapons in a house close to the wall. Once they were attacked by enemies; they were in a crush to get their weapons and they killed one another more than what the enemies killed. They instituted that everybody should take from his house.”