Hadith 337

Bulugh al-Maram

Book 2: The Book of Prayer
Hadith 337
وَلِلْبُخَارِيِّ: { ثُمَّ هَاجَرَ, فَفُرِضَتْ أَرْبَعًا, وَأُقِرَّتْ صَلَاةُ اَلسَّفَرِ عَلَى اَلْأَوَّلِ } 1‏ .‏
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).'