Jami` at-Tirmidhi 3300

Ali bin Abi Talib said:“When (the following) was revealed: ‘O you who believe! When you consult the Messenger in private, spend something in charity before your private consultation.’ The Prophet said to me: ‘What do you think? A dinar?’ I said: ‘They will not be able to.’ He said: ‘Then half a Dinar?’ I said: ‘They will not be able.’ He said: ‘Then how much?’ I said ‘A barely corn.’ He said: ‘You made it too little.’” He said: “So the Ayah was revealed: ‘Are you afraid of spending in charity before your private consultation?’ He said: “It was about my case for which Allah lightened the burden upon this Ummah.”