Musnad Ahmad 32:1097

Muhammad ibn Bakr narrated to us, Hisham ibn Hassan informed us, and Rawh narrated to us, Hisham ibn Hassan narrated to us, from Marwan, the freed slave of Hind bint al-Muhallab. Rawh said: Hind sent me to Anas ibn Malik—and he did not say "the wife of the Prophet, may Allah bless him and grant him peace"—for a need. I heard him narrating to his companions that he heard the Prophet, may Allah bless him and grant him peace, forbid *al-wisal* (continuous fasting without breaking it at night).