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This is the supplication of Imam al-Hasan al-Askari (alaihi salam) which must be read thrice every morning for protection. This dua was initially posted by brother Syed Ahmad Amiruddin.
Blog on Ahlul Bayt for Ahle Sunnah.
It is a well-known fact that the Prophet had an admirable sense of humour - although even in witticism, he never spoke but truth. Once an old lady of Medina asked him to pray to Allah to give her a place in the Paradise. The Prophet said, "Old women would not enter the Paradise." She went out crying. Bilal saw her and asked her why she was crying. She narrated the whole episode. Bilal came with the lady to the Prophet, and said, "This woman is narrating such and such from you?" The Prophet said, "Even black men would not enter the Paradise." Now Bilal too started crying. Then 'Abbas, the uncle of the Prophet reached there and learning of the episode, tried to intercede with the Prophet, who told him that even old men would not enter the Paradise. When he too joined the crying group, the Prophet told them to be cheerful because Allah would create them young and with bright faces and then they would go into Paradise
al-Majlisi, Hayatu'l Qulub, pp. 129-130; Bihar, vol. 16, p. 295.
http://www.al-islam.org/slavery/4.htm