Muwatta Malik, Book 20, Hadith 904 (In-Book)

Yahya related to me from Malik from Ibn Shihab from Salim ibn Abdullah from Abdullah ibn Umar that the Messenger of Allah, may Allah bless him and grant him peace, prayed maghrib and isha together at Muzdalifa.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى الْمَغْرِبَ وَالْعِشَاءَ بِالْمُزْدَلِفَةِ جَمِيعًا ‏.‏

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also referenced under: Book 20, Hadith 205 (USC-MSA)