(37) باب صَوْمِ سَرَرِ شَعْبَانَ
'Imran b. Husain (Allah be pleased with them) reported that the Messenger of Allah (ﷺ) said to a person:
Did you observe fast in the middle of this month. i. e. Sha'ban? He said: No. Thereupon he said to him: When it is the end of Ramadan, then observe fast for one day or two (Shu'ba had some doubt about it) but he said: I think that he has said: two days.
Reference: Sahih Muslim 1161 d
In-book reference: Book 13, Hadith 259
USC-MSA web (English) reference(deprecated numbering scheme): Book 6, Hadith 2609