Imam Hasan Askari (a.s.) wrote to Ishaq bin Ismail that the Lord of the Might, through His Mercy and kindness, made some things obligatory for you. It was not because Allah needed it. Rather it is Grace from Allah except Whom there is no Allah for you, so that He may separate the unholy from the holy and so that He may take your trial about the things which are in your hearts and may make pure the things which are in your hearts through it so that you may advance towards His Mercy and so that