Musnad Ahmad 27:304

Waki’ narrated to us, from al-‘Umari, from Nafi’, from Ibn ‘Umar, that the Prophet (peace and blessings of Allah be upon him) forbade *wisal* (continuous fasting without breaking it) in fasting. It was said to him: "You do it." He said: "I am not like one of you; I spend the night while my Lord feeds me and gives me to drink."