Muwatta Malik, Book 9, Hadith 339 (In-Book)

Yahya related to me from Malik from Nafi that Abdullah ibn Umar, shortened the prayer when he left for hajj or umra at Dhu'l Hulayfa.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ إِذَا خَرَجَ حَاجًّا أَوْ مُعْتَمِرًا قَصَرَ الصَّلاَةَ بِذِي الْحُلَيْفَةِ ‏.‏

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also referenced under: Book 9, Hadith 11 (USC-MSA)