يَصُومُ الْعَشْرَ وَثَلاَثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ الاِثْنَيْنِ وَالْخَمِيسَ .
It was narrated from Hunaidah bin Khalid, from his wife, that one of the wives of the Prophet said: "The Prophet used to fast the ten (days), and three days of each month: Monday and Thursday."