Muwatta
Malik
موطأ مالك
09
Shortening the Prayer
كتاب قصر الصلاة فى السفر
Chapter 7: Voluntary Prayers while Travelling, by Day and at Night, and Praying on a Riding Beast
Muwatta Malik 357
Yahya related to me that Malik said, "I have heard from Nafi that Abdullah ibn Umar used to see his son, Ubaydullah ibn Abdullah, doing voluntary prayers on a journey,and he would not disapprove of it."
وَحَدَّثَنِي عَنْ مَالِكٍ، قَالَ بَلَغَنِي عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَرَى ابْنَهُ عُبَيْدَ اللَّهِ بْنَ عَبْدِ اللَّهِ يَتَنَفَّلُ فِي السَّفَرِ فَلاَ يُنْكِرُ عَلَيْهِ .