Maliks Muwatta Book 45, Hadith Number 26.

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.”