Hadith 341

Narrated 'Aishah (RA) that when the Salat (prayer) was first prescribed, it consisted of two Rak'at. Afterwards, the prayer during travelling was confirmed (as two Rak'at), while the prayer at the place of residence was completed (as four Rak'at). [Agreed upon]. al-Bukhari has: 'Then [(Allah's Messenger (ﷺ)] emigrated and it was prescribed as four, but prayer while travelling was left according to the original prescription (of two Rak'at).' Ahmad added, 'Except the Maghrib (prayer) for it is the Witr (prayer) of the day; and except the Fajr (prayer), since the recitation (of the Qur'an) is prolonged in it.'