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 heused to travel to Khaybar and he would shorten the prayer. Translation Not Available

Book Ref: Muwatta Imam Malik Book 9 Hadith 342
Web Ref:  Muwatta Imam Malik Book 9 Hadith 14