Amr bin Shu'aib, narrating from his father, from his grandfather, reports that Sayyiduna Bilal (may Allah be pleased with him) came to the Prophet Muhammad (peace be upon him) with the 'ushr (tithe) of his land. He asked the Prophet (peace be upon him) to grant him a valley as a pasture, which was called Salbah. The Prophet (peace be upon him) granted him that place as a pasture. Then, when Sayyiduna Umar (may Allah be pleased with him) became the caliph, Sufyan bin Wahb wrote a letter to Sayyiduna Umar (may Allah be pleased with him) and asked him about this matter. Sayyiduna Umar (may Allah be pleased with him) replied: He will pay you the same as he used to pay the Prophet (peace be upon him), that is, one-tenth of the produce of that place. So, it is fine, let the pasture remain with him, which is called Salbah, and if he does not do so, then it will be as if anyone who wishes may eat from it.