Muwatta Malik
Shortening the Prayer
Hadith #14
9.14
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّهُ كَانَ يُسَافِرُ إِلَى خَيْبَرَ فَيَقْصُرُ الصَّلاَةَ .
Yahya related to me from Malik from Nafi from Ibn Umar that he used to travel to Khaybar and he would shorten the prayer