Sunan al-Nasa'i The Book of Fasting Abu Nasr al-Tamar أبو نصر التمار Asim al-Ahwal عاصم الأحول Hammad bin Salama حماد بن سلمة Umm Salamah “The Messenger of Allah used to be keen to fast on Mondays and Thursday.” https://parallelquran.com/hadith/sunan-al-nasai-2365/