‘Amir b. Rabi'a said that they prayed the morning prayer behind ‘Umar b. al-Khattab and that he recited slowly in both rak'as Sura Yusuf and Sura al-Hajj (Al-Qur’an; 22). When someone remarked that he must have begun the prayer at break of day he replied that that was so. Malik transmitted it.
Hadith Referenceمشكوة المصابيح / كتاب الصلاة / 865
Hadith Gradingالألبانی:صَحِيح | زبیر علی زئی:إسناده صحيح
Hadith Takhrij´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «إسناده صحيح، رواه مالک (1/ 82 ح 180)»