“I once wrote to abu Muhammad (a.s.), and asked, ‘A man had a canal in a village and another man wanted to dig another canal in a village that belonged to him. How much distance is required between the two so that they do not harm each other when the land is solid or soft? He (the Imam) signed the answer that said, ‘It is according to a measure that does not cause one to harm the other, by the will of Allah.’ I wrote to him (the Imam) (a.s.), about a man who had a flour mill on the canal of a village that belonged to a man and the owner of the village wanted to divert the water to his village in another canal and put the flour mill out of work; if he can do so. He (the Imam) (a.s.), signed the answer that said, ‘He must be pious before Allah and act according to what is acceptable among people and must not cause harm to his believing brother.’”