Fiqh-us-Sunnah - 5.87

Hadith 5.87.1

Prerequisites for Sa'i

For Sa'i to be valid and acceptable, it must meet the following conditions: Should be performed after tawaf.
Must be performed in seven rounds.
Must begin from Safa and end at Marwah.
Must be performed in Al-Mas'a, the path between Safa and Marwah, because the Prophet (peace be upon him) did so, and moreover he explicitly told us: "Take your (religious) rites from me."
Therefore, a Sa'i performed without performing tawaf prior to it, or one that starts from Marwah and ends at Safa, or is performed in a place other than the specified area (between Safa and Marwah), is void. (The Hanafi school holds that Sa+i after tawaf and beginning it at Safa and ending it at Marwah, are two essential conditions for the validity of Hajj . Thus if someone made a Sa+i before making tawaf, or begins his Sa+i at Marwah, and ends it at Safa, his Sa+i is valid, but he is required to slaughter an animal)