Hadith 4:510
Ali ibn Mushir narrated to us, from al-Shaybani, who said: Abu Mariyah informed me, saying: I heard Ali saying: "Whoever has begun [the day without fasting], let him complete it [by abstaining from food], and whoever has eaten, let him fast [the remainder of the day]."
حدثنا علي بن مسهر عن الشيباني قال أخبرني أبو مارية قال سمعت عليا يقول فمن كان بدا فليتم ومن كان أكل فليصم