يَصُومُ مِنْ كُلِّ شَهْرٍ ثَلاَثَةَ أَيَّامٍ الاِثْنَيْنِ وَالْخَمِيسَ مِنْ هَذِهِ الْجُمُعَةِ وَالاِثْنَيْنِ مِنَ الْمُقْبِلَةِ .
It was narrated that Umm Salamah said: "The Messenger of Allah used to fast three days of every month: the Monday and Thursday of the first week and the Monday of the following week."