Muwatta Imam Malik Book of Shortening the Prayer, Hadith 16

Yahya related to me from Malik from Nafi that he used to travel one mail-stage with Ibn Umar, and he would not shorten the prayer.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّهُ كَانَ يُسَافِرُ مَعَ ابْنِ عُمَرَ الْبَرِيدَ فَلاَ يَقْصُرُ الصَّلاَةَ .