Sunan an-Nasa'i #2130 · The Book of Fasting

Sunan an-Nasa'iIt was narrated that Ibn 'Abbas said
Sunan an-Nasa'i · Book 22 · The Book of Fasting
Sunan an-Nasa'i · كتاب 22 · كتاب الصيام
"The Messenger of Allah said: "The Messenger of Allah 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 ‏"‏ ‏.‏
Reference : Sunan an-Nasa'i 2130In-book reference : Book 22, Hadith 41