Bulugh al-Maram 5 Fasting كتاب الصيام 5

وَعَنِ اِبْنِ عُمَرَ رَضِيَ اَللَّهُ عَنْهُمَا قَالَ: { تَرَاءَى اَلنَّاسُ اَلْهِلَالَ, فَأَخْبَرْتُ رَسُولَ اَللَّهِ – صلى الله عليه وسلم -أَنِّي رَأَيْتُهُ, فَصَامَ, وَأَمَرَ اَلنَّاسَ بِصِيَامِهِ } رَوَاهُ أَبُو دَاوُدَ, وَصَحَّحَهُ اِبْنُ حِبَّانَ, وَالْحَاكِمُ 1 . 1 – صحيح. رواه أبو داود ( 2342 )، وابن حبان ( 3438 )، والحاكم ( 1 / 423 ).

Ibn ’Umar (RAA) narrated, ‘The people were trying to sight the new moon (of Ramadan.) and when I reported to the Messenger of Allah (صلى الله عليه وسلم) that I had seen it, he fasted and commanded people to fast.’ Related by Abu Dawud, and Al-Hakim and Ibn Hibban graded it as Sahih.