Sunan an-Nasa'i
It was narrated that Ibn 'Abbas said: "The Messenger of Allah (ﷺ) said: "The Messenger of Allah (ﷺ) said: Do not fast before Ramadan. Fast when you see it and stop fasting when you see it, and if clouds prevent you from seeing it, then complete Thirty (Days)."'
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو الأَحْوَصِ، عَنْ سِمَاكٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ تَصُومُوا قَبْلَ رَمَضَانَ صُومُوا لِلرُّؤْيَةِ وَأَفْطِرُوا لِلرُّؤْيَةِ فَإِنْ حَالَتْ دُونَهُ غَيَايَةٌ فَأَكْمِلُوا ثَلاَثِينَ " .
Grade: Sahih (Darussalam)
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