وَعَنْ أُمِّ سَلَمَةَ
قَالَتْ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَأْمُرُنِي أَنْ أَصُومَ ثَلَاثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ أَوَّلُهَا الِاثْنَيْنِ وَالْخَمِيس
God’s messenger used to command her to fast three days every month beginning with Monday or Thursday. Abu Dawud and Nasai transmitted it.
Mishkat al-Masabih 1969, Book 8, Fasting, Hadith 103. 1 min read