Maliks Muwatta Book 9, Hadith Number 14.
Section : Circumstances in Which the Prayer Has To Be Shortened.
Yahya related to me from Malik from Nafi from Ibn Umar that he used to travel to Khaybar and he would shorten the prayer.
Yahya related to me from Malik from Nafi from Ibn Umar that he used to travel to Khaybar and he would shorten the prayer.