Narrated Umm Salamah, Ummul Muminin: Hunaydah al-Khuzai reported on the authority of her mother who said: I entered upon Umm Salamah and asked her about fasting. She said: The Messenger of Allah ﷺ used to command me to fast three days every month beginning with Monday or Thursday.
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Explanation & Benefits
Hafiz Muhammad Ameen
(1) "He used to command." That is, as a recommendation (mustahabb).
(2) "The first Thursday." In previous narrations, mention is made of the first Monday. The intent is that if the first Thursday arrived, then he would fast on Thursday, Monday, and then the next Monday; and if Monday came first at the beginning of the month, then he would fast on Monday, Thursday, and then the following Thursday. That is, the three fasts would be confined to Mondays and Thursdays. Whether the beginning is from Thursday or Monday, there is no difference.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 2421