Hadith #2365 (Sunan al-Nasa'i)
Book: The Book of Fasting
Narrator(s): 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.”

Source: https://parallelquran.com/hadith/sunan-al-nasai-2365/