Musnad Ahmad 30:377

Yazid narrated to us, Muhammad informed us, from Musa ibn Yasar, from Abu Hurairah, and from Abu al-Zinad, from al-A'raj, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Beware of continuous fasting (wisal)." 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 drink. So, take upon yourselves of deeds that which you have the capacity for."