Jewish Babylonian Talmud – Tracts Erubin – Regulations concerning the combining of roofs on Sabbath.
p. 214 CHAPTER IX. REGULATIONS CONCERNING THE COMBINING OF ROOFS ON SABBATH. MISHNA: All the roofs of a town are considered one private ground (although the houses underneath are occupied by several), provided there be not one roof ten hands higher or ten hands lower than the rest. Such is the dictum of R. Meir; the sages, however,
