Hadith 300:12
Ishaq ibn Isa narrated to us, Muhammad ibn Jabir informed us, from Qays ibn Talq, from his father, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Indeed, Allah the Almighty and Majestic has made these crescents as timing markers for the people. So fast when you see it, and break your fast when you see it. But if it is obscured from you, then complete the count."
حدثنا إسحاق بن عيسى، أخبرنا محمد بن جابر، عن قيس بن طلق، عن أبيه قال: قال رسول الله صلى الله عليه وسلم: " إن الله عز وجل جعل هذه الأهلة مواقيت للناس، صوموا لرؤيته، وأفطروا لرؤيته، فإن غم عليكم فأتموا العدة "