Musnad Ahmad 30:1062

The Messenger of Allah, may Allah bless him and grant him peace, said: "Beware of *wisal* (continuous fasting without breaking it at night), beware of *wisal*." They said: "You practice *wisal*, O Messenger of Allah." He said: "I am not like you in that regard. 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."