Eruvin עירובין

On the Sabbath one may not carry from a private domain into a public one. But a courtyard shared by several families—whose is it? The sages gave a way: the residents join together with bread, and the courtyard becomes one household. Hence "eruv"—a mingling, a joining.

The second subject is the limit beyond which one does not walk on the Sabbath, and the way of shifting where it begins. The tractate is reckoned the hardest in the Talmud: it is all measurements, walls, openings and diagrams. Here too is said of the dispute of the schools of Shammai and Hillel: "these and these are the words of the living God."

Order: Moed. There is Gemara in both the Babylonian and the Jerusalem Talmud.