Raising the voice when saying Takbir
باب مَا يُكْرَهُ مِنْ رَفْعِ الصَّوْتِ فِي التَّكْبِيرِ
Sahih al-Bukhari, Book of Fighting for the Cause of Allah (Jihaad)(view book)
Sahih al-Bukhari 2992
Narrated Abu Musa Al-Ashari:
We were in the company of Allah's Apostle (during Hajj). Whenever we went up a high place we used to say: "None has the right to be worshipped but Allah, and Allah is Greater," and our voices used to rise, so the Prophet ﷺ said, "O people! Be merciful to yourselves (i.e. don't raise your voice), for you are not calling a deaf or an absent one, but One Who is with you, no doubt He is All-Hearer, ever Near (to all things)."
حَدَّثَنَا مُحَمَّدُ بْنُ يُوسُفَ، حَدَّثَنَا سُفْيَانُ، عَنْ عَاصِمٍ، عَنْ أَبِي عُثْمَانَ، عَنْ أَبِي مُوسَى الأَشْعَرِيِّ ـ رضى الله عنه ـ قَالَ كُنَّا مَعَ رَسُولِ اللَّهِ ﷺ، فَكُنَّا إِذَا أَشْرَفْنَا عَلَى وَادٍ هَلَّلْنَا وَكَبَّرْنَا ارْتَفَعَتْ أَصْوَاتُنَا، فَقَالَ النَّبِيُّ ﷺ " يَا أَيُّهَا النَّاسُ، ارْبَعُوا عَلَى أَنْفُسِكُمْ، فَإِنَّكُمْ لاَ تَدْعُونَ أَصَمَّ وَلاَ غَائِبًا، إِنَّهُ مَعَكُمْ، إِنَّهُ سَمِيعٌ قَرِيبٌ، تَبَارَكَ اسْمُهُ وَتَعَالَى جَدُّهُ ".