عَنْ حَفْصَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ أَرْبَعٌ لَمْ يَكُنْ يَدَعُهُنَّ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ صِيَامَ عَاشُورَاءَ وَالْعَشْرِ وَثَلَاثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ وَالرَّكْعَتَيْنِ قَبْلَ الْغَدَاةِ
It is narrated from Sayyida Hafsa (may Allah be pleased with her) that the Noble Prophet (peace and blessings be upon him and his family) would not abandon four things: the fast of Ashura, the fasts of the ten days, the fasts of three days from every month, and the two Sunnah (units) before Fajr.