On the third day as they sat down to break the fast...
On the third day as they sat down to break the fast, a prisoner knocked at their door asking for something to eat. Although the people of the house of the Holy Prophet had been suffering from near starvation for the last three days, they again gave away all the bread to the prisoner and contented themselves only with water for the third day in succession.
It was in appreciation of these sacrifices, that Almighty Allah revealed the whole 'Surah al-Dahr', which contains, among other things, the following Ayat: “They (Ahlul Bait) fulfil vow and fear a day the evil of which shall be spreading far and wide” (Surah Al-Dahr, 76: Verse7) This is how Ahlul Bait, the people of the household of the Holy (S), kept and fulfilled their their Nazr (vow). They also set example of sacrifice by feeding the poor and caring for those who were in need.
The tradition of Nazr is a very old one. During the time of Bani Israel, centuries back, in the name of God, people used to present their sons at Baitul-Muqaddas, in the service of the pious people there, They used to stay within the walls of the mosques. Once Imran, the father of Hazrat Maryam (Mary) got the good news that Almighty would bless him with a child.
The child would be so gifted that with the command of God, he would cure the sick, restore sight to the blind, bring life back unto the dead and he shall also be a Prophet of God. When Bibi Hanna, the mother of Hazrat Maryam, heard this news, she vowed that she would free the child from the worldly attachments (to spend life in the service of Allah).
The following Ayat in the Qur'an refers to this event: “When said (Hanna) the wife of lmran, 'My Lordl Verily I have vowed to thee what is in my womb to be (dedicated) for Thee (exclusively for Thy service) freed (from all worldly responsibilities), therefore accept (it) from me; Verily Thou Ant the All-Hearing, the All-Knowing'“. (Sura Ale-Imran, 3:35) Over 2000 years ago people worshipped idols in Arabia. There was a King by the name of Hasan who decided to destroy the Holy Ka'aba.
Because of this evil intention, he fell sick and ended being a leper. Upon realising his mistake, he begged pardon from God and vowed that if his health was restored, he would place Ghilaf (Covering) over the Holy Ka'aba. This wish of his was fulfilled and he, in turn placed the Ghilaf made of palm leaves, For many years a new black cover made of thick cloth is being placed on Ka'aba every year.