Hadith 503330
Chapter 9: Shortening the Prayer - كتاب قصر الصلاة فى السفر
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ إِذَا جَمَعَ الأُمَرَاءُ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ فِي الْمَطَرِ جَمَعَ مَعَهُمْ .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to join the prayer along with the amirs if they joined maghrib and isha in the rain.
Reference Muwatta Malik 503330
USC-MSA web (English) reference : Book 9, Hadith 5