“Upon asking him (the Imam) (a.s.), about the case of a man who buys a pasture for fifty dirham or less or more and he wants to allow entering the pasture whoever wants to enter so that he charges them for it. He (the Imam) said, ‘He can allow whomever he wants with a payment of part of what he has paid. If he enters the pasture with a payment of forty-nine and his sheep (graze) for one dirham, it is not unlawful. He cannot receive payment of fifty dirham and his sheep graze along with them or for more than fifty but his sheep do not graze with them, unless he has done a certain work in the pasture, like digging a well, or a canal or has experienced fatigue in it with the consent of the owners of the pasture, in which case it is not unlawful to sell it for more than for what he has bought, because he has done certain work in it and with this it becomes valid for him.’”