Ibn-Abbas narrated that Hassan and Husayn (Radhi Allahu Anhum) were sick. The Prophet (Sallallahu alayhi wa aalihi wa salam) and a group of followers came to visit them. They suggested to Sayyidina Ali (Karamallahu wajhah)to take a vow for their recovery. So, Sayydina Ali, Sayyidatina Fatima (Radhi Allahu anhum)and Fezza (their house-helper) took a vow that if Hassan and Hosain recovered, they would fast for three days. (According to the same narration, Hassan and Hosain (radhi Allahu anhum) made the same vow.)
After a short while both of them recovered. Therefore, the family fasted for the first day, but, as they were in dire need for food stuffs,Sayyidina Ali borrowed some barley and Sayyidatina Fatima ground one-third of it into flour and baked some bread.
With the onset of evening, when they were preparing to break their fasts, an indigent person came to their door and said, "Peace be upon you, the Household of Mohammad. I am a needy Muslim, so please give me some food. May Allah bestow upon you, in kind, from divine sustenance." All of them gave priority to him and gave him their shares. That night, they broke their fast with only water.
The following day they fasted again, but, like the previous day, an orphan came to the door. Once more, they forfeited their bread and ate nothing but water.
The next day, they fasted for the third time. This day a captive came to their house and they repeated their charity.
On the fourth day, Sayyidina Ali took Sayyidina Hassan and Sayyidina Husayn with himself to see the Prophet Sallallahu alayhi wa aalihi wa salam. When the Prophet Sallallahu alayhi wa aalihi wa salam observed their condition; they were trembling with hunger, he said, "It grieves me to see you in this condition,
Then, he stood up and walked with them. When he arrived at their home, he found Sayyidatina Fatima Radhi Allahu Anha praying. Her stomach was sunk in to her backbone and her eyes had become sunken, too. The Prophet was greatly affected. At this moment Sayyidina Jibrail Alaihi salam descended and said, "O, Mohammad receive this Sura. Allah congratulates you for having such a family.. And then Sayyidina Jibrail Alaihi salam recited, to him, Sura Hal-ata.[1]