Fast on the 15th of Sha'ban

Sayyiduna Ali (Radi Allahu Anhu) has reported that the Holy Prophet (SallAllahu Alayhi wa Sallam) said,

"When the 15th Night of Sha'ban comes, do Qiyam (for worship) in the night and observe fast during the day. No doubt, Allah reveals a special Divine Manifestation on the sky above the earth from the time of sunset and announces, ‘Is there anyone seeking forgiveness so that I may forgive him? Is there anyone seeking sustenance so that I may grant him sustenance? Is there anyone afflicted so that I may relieve his affliction? Is there so and so...’ He keeps announcing this until the time of Fajr."

[Sunan Ibn Majah, Vol. 2, Page 160, Hadith 1388]