كتاب الصلاة
5  
The Book of Salah
(3)
Chapter: How The Salah Was Made Obligatory
(3)
باب كَيْفَ فُرِضَتِ الصَّلاَةُ ‏.‏
Sunan an-Nasa'i 455
It was narrated that 'Aishah said:
"The Salah was enjoined two Rak'ahs at a time, then the Salah when traveling remained like that, but the Salah while resident was increased."
أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ صَالِحِ بْنِ كَيْسَانَ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، قَالَتْ فُرِضَتِ الصَّلاَةُ رَكْعَتَيْنِ رَكْعَتَيْنِ فَأُقِرَّتْ صَلاَةُ السَّفَرِ وَزِيدَ فِي صَلاَةِ الْحَضَرِ ‏.‏
Grade: Sahih (Darussalam)
Reference : Sunan an-Nasa'i 455
In-book reference : Book 5, Hadith 8
English translation : Vol. 1, Book 5, Hadith 456