وَعَنِ ابْنِ عُمَرَ
قَالَ: تَرَاءَى النَّاسُ الْهِلَالَ فَأَخْبَرْتُ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِنِّي رَأَيْتُهُ فَصَامَ وَأَمَرَ النَّاسَ بِصِيَامِهِ
The people tried to see the new moon and he informed God’s messenger that he had seen it, so he fasted and commanded the people to observe the fast.