'Aishah (May Allah be pleased with her)u reported:
The Messenger of Allah (ﷺ) used to observe fast on Mondays and Thursdays.[At-Tirmidhi]. (JA)
App reference (JA): Book 9, Hadith 267 (JA)
Arabic/English book reference (JA): Book 9, Hadith 1257 (JA)