Narrated Abu Musa Al-Ash`ari:We were in the company of Allah's Messenger (ﷺ) (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 صلى الله عليه وسلم، فَكُنَّا إِذَا أَشْرَفْنَا عَلَى وَادٍ هَلَّلْنَا وَكَبَّرْنَا ارْتَفَعَتْ أَصْوَاتُنَا، فَقَالَ النَّبِيُّ صلى الله عليه وسلم " يَا أَيُّهَا النَّاسُ، ارْبَعُوا عَلَى أَنْفُسِكُمْ، فَإِنَّكُمْ لاَ تَدْعُونَ أَصَمَّ وَلاَ غَائِبًا، إِنَّهُ مَعَكُمْ، إِنَّهُ سَمِيعٌ قَرِيبٌ، تَبَارَكَ اسْمُهُ وَتَعَالَى جَدُّهُ ".
Bukhari
Fighting for the Cause of Allah (Jihaad) • Hadith 201