Muwatta Malik 338

حَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، رَكِبَ إِلَى ذَاتِ النُّصُبِ فَقَصَرَ الصَّلاَةَ فِي مَسِيرِهِ ذَلِكَ ‏.‏ قَالَ مَالِكٌ وَبَيْنَ ذَاتِ النُّصُبِ وَالْمَدِينَةِ أَرْبَعَةُ بُرُدٍ ‏.‏

Yahya related to me from Malik from Nafi from Salim ibn Abdullah that Abdullah ibn Umar rode to Dhat an-Nusub and shortened the prayer on the journey. Malik said, "There are four mail-stages between Dhat an-Nusub and Madina

Reference

Muwatta Malik 338

In-book

Book 9, Hadith 13