Sahih al-Bukhari 774
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · To recite aloud in the Fajr (early morning) prayer.
Narrated Ibn `Abbas:
حَدَّثَنَا مُسَدَّدٌ ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ ، قَالَ حَدَّثَنَا أَيُّوبُ ، عَنْ عِكْرِمَةَ ، عَنِ ابْنِ عَبَّاسٍ ، قَالَ قَرَأَ النَّبِيُّ صلى الله عليه وسلم فِيمَا أُمِرَ، وَسَكَتَ فِيمَا أُمِرَ {وَمَا كَانَ رَبُّكَ نَسِيًّا} {لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللَّهِ أُسْوَةٌ حَسَنَةٌ} .
The Prophet (ﷺ) recited aloud in the prayers in which he was ordered to do so and quietly in the prayers in which he was ordered to do so. "And your Lord is not forgetful." "Verily there was a good example for you in the ways of the Prophet."