Hadith
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
Sahih · Salim al-Hilali
Muwatta Malik 339 ·Book 9, Hadith 14·Also available on sunnah.com·