“I once wrote to abu al-Hassan (a.s.), about the case of a man who made a will about a part of the one-third of his legacy after his death from the income of a certain asset that belonged to him. He instructed the executor of his will to spend half of it for the causes he mentioned every year and with the rest of the one-third he can do whatever he wanted. The executor of the will executed what the deceased wanted about the known causes. About the remaining he said that he has given it to so and so and so and so every year, for al-Hajj such and such amount, and for charity such and such amount every year. He then decided to change all of such causes. He said that he has decided to spend for causes other than those he wanted before; if he can do such changes and alterations of such nature reducing and including other causes if he wanted. He (the Imam) wrote the answer that said, ‘He can do whatever he wants except if he has written upon himself for doing certain things.’”