Musnad Ahmad 27:1458

Ishaq narrated to us, Malik narrated to us, from Nafi’, from Ibn Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) forbade *al-wisal* (fasting continuously for days without breaking the fast). It was said: "Are you not practicing *wisal*?" He said: "I am fed and given to drink."