My beloved ﷺ instructed me to observe three things which I will never abandon, Allah willing. He instructed me to pray the forenoon prayer, to perform the witr prayer before sleeping, and to fast three days of every month.
أوصاني حبيبي ﷺ بثلاثة لا أدعهن إن شاء الله تعالى أبدا. أوصاني بصلاة الضحى، وبالوتر قبل النوم، وبصيام ثلاثة أيام من كل شهر.
Nasai (2404) narrated it from Ali bin Hajar, who said, Ismail narrated to us, Muhammad bin Abu Harmala narrated to us, from Ata bin Yasar, from Abu Dharr, and he mentioned it. Its isnad is sahih. Ibn Khuzayma (1083) also graded it sahih, narrating it from Ali bin Hajar Saadi, as did Ahmad (21518) from Sulayman bin Dawud Hashimi, both of them from Ismail with the same wording.Ismail is Ibn Jafar bin Abu Kathir Ansari Zarqi, one of the narrators found in all six major collections.