Muwatta Malik, Book 20, Hadith 26 (USC-MSA)

Yahya related to me from Malik from a reliable source that Abdullah ibn Umar once entered ihram at Ilya (Jerusalem).

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ الثِّقَةِ، عِنْدَهُ أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، أَهَلَّ مِنْ إِيلْيَاءَ ‏.‏

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also referenced under: Book 20, Hadith 734 (In-Book)