Hadith 8:2548
Abu Bakr narrated to us, he said: Ibn Abi Za'idah narrated to us, from Ibn Jurayj, from Nafi', who said: Ibn Umar used to consider the departure from Arafat [to be permissible] when the night became apparent and the fasting person broke his fast.
حدثنا أبو بكر قال نا بن أبي زائدة عن بن جريج عن نافع قال كان بن عمر يرى الدفعة من عرفة إذا تبين الليل وأفطر الصائم