Muhammad bin Isma'il bin Ibrahim محمد بن إسماعيل بن إبراهيم بن مقسم · The Book on Fasting

"A Bedouin came to the Prophet and said: 'I have seen the crescent.' So he said: 'Do you testify that none has the right to be worshipped but Allah? Do you testify that Muhammad is the Messenger of Allah?' He said: 'Yes.' So he said: 'O Bilal! Announce to the people that they should fast tomorrow.'"

the Prophet said: "The fast is the day the people fast, the breaking of the fast is the day the people break their fast, and the sacrifice is the day the people sacrifice."

"I went to Anas bin Malik during Ramadan" and he mentioned a similar narration (as no. 799).