Shama-il Tirmidhi Chapter 42, Hadith Number 1 (281).
‘Abdullah bin Shaqeeq Radhiyallahu ‘Anhu reports: “I inquired from ‘Aayeshah Radhiyallahu ‘Anha regarding the (nafil) saum of Rasulullah Sallallahu ‘Alayhi Wasallam. She replied: ‘At times Rasulullah Sallallahu ‘Alayhi Wasallam fasted continuously. We used to say, he will keep on fasting…