Musnad Ahmad 30:1426

'Affan narrated to us, Sulaym ibn Hayyan narrated to us, he said: I heard my father, he said: I heard Abu Hurayrah, from the Prophet, may Allah bless him and grant him peace, he said: "Beware of continuous fasting (al-wisal)," twice. They said: "But you practice continuous fasting, O Messenger of Allah." He said: "I am not like you in that. I spend the night while my Lord feeds me and gives me to drink. So do not burden yourselves with deeds that you do not have the capacity for."