Narrated byto us by Ibn Fudayl, who said
Arabic (Original)
حَدَّثَنَا ابْنُ فُضَيْلٍ قَالَ حَدَّثَنَا الْحَسَنُ بْنُ عُبَيْدِ اللَّهِ حَدَّثَنَا هُنَيْدَةُ الْخُزَاعِيُّ عَنْ أُمِّهِ قَالَتْ دَخَلْتُ عَلَى أُمِّ سَلَمَةَ فَسَأَلْتُهَا عَنْ الصِّيَامِ فَقَالَتْ كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَأْمُرُنِي أَنْ أَصُومَ ثَلَاثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ أَوَّلُهَا الِاثْنَيْنِ وَالْجُمُعَةُ وَالْخَمِيسُ.
English Translation
Narrated to us by Ibn Fudayl, who said: al-Hasan ibn 'Ubaydullah narrated to us: Hunaydah al-Khuza'i narrated to us, from his mother, who said: "I went in to see Umm Salamah and asked her about fasting. She said: 'The Prophet (peace and blessings be upon him) used to command me to fast three days from every month, the first of them being Monday, and also Friday and Thursday.'"