It wasnarrated from Mu'adhah Al-'Adawiyyah that 'Aishah said:
"TheMessenger of Allah (ﷺ) used to fast three days of each month." Isaid: "Which were they?" She said: "He did not care which daystheywere." (JA)
English reference (JA): Vol. 1, Book 7, Hadith 1709 (JA)
Arabic reference (JA): Book 7, Hadith 1780 (JA)