Authentic
graded by Al-Albani
Mishkat al-Masabih 865
وَعَنْ عَبْدُ اللَّهِ بْنِ عَامِرِ بْنِ رَبِيعَةَ قَالَ: صلينَا وَرَاء عمر ابْن الْخطاب الصُّبْح فَقَرَأَ فيهمَا بِسُورَةِ يُوسُفَ وَسُورَةِ الْحَجِّ قِرَاءَةً بَطِيئَةً قِيلَ لَهُ: إِذًا لَقَدْ كَانَ يَقُومُ حِينَ يَطْلُعُ الْفجْر قَالَ: أجل. رَوَاهُ مَالك
‘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.
Reported by Malik (No. 183). Cited in Mishkat al-Masabih (No. 865).