Muwatta Malik, Book 45, Hadith 26 (USC-MSA)

Yahya related to me that Malik said, "I heard that Umar ibn al- Khattab said, 'A night in Rukba (a valley near Taif,) is more preferable to me than ten nights in ash-Sham.' " Malik said, "He meant to lengthen and preserve their lives because of the severity of the plague in ash-Sham."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ قَالَ بَلَغَنِي أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ لَبَيْتٌ بِرُكْبَةَ أَحَبُّ إِلَىَّ مِنْ عَشَرَةِ أَبْيَاتٍ بِالشَّامِ ‏.‏ قَالَ مَالِكٌ يُرِيدُ لِطُولِ الأَعْمَارِ وَالْبَقَاءِ وَلِشِدَّةِ الْوَبَإِ بِالشَّامِ ‏.‏

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also referenced under: Book 45, Hadith 1625 (In-Book)