Anas bin Malik reported,

And Abu Bakr bin Nafi narrated to me, and the wording is his, Bahz narrated to us, Hammad narrated to us, Thabit narrated to us, from Anas , that the Messenger of Allah ﷺ would fast until it was said, "He has fasted, he has fasted," and he would break his fast until it was said, "He has stopped fasting, he has stopped fasting."

و حدثني زهير بن حرب وابن أبي خلف قالا حدثنا روح بن عبادة حدثنا حماد عن ثابت

عن أنس رضي الله عنه

ح و حدثني أبو بكر بن نافع واللفظ له حدثنا بهز حدثنا حماد حدثنا ثابت عن أنس رضي الله عنه أن رسول الله ﷺ كان يصوم حتى يقال قد صام قد صام ويفطر حتى يقال قد أفطر قد أفطر