Shaikh Ibn ul-‘Uthaymeen said rahimahullah
“… So like this, some people make the mistake in the Janazah prayer specifically. If the Imam makes takbir, they raise their voices: Allahu Akbar. Some of them do this in the additional Takbir of the Eid prayer. If the Imam says: Allahu Akbar…Allahu Akbar. They raise their voices with the Takbir, I mean, those behind the Imam. This is the mistake. The one behind the Imam makes Takbir quietly and glorifies Allah quietly and supplicates to Allah quietly”
[Taken from: Liqaa Baba al-Maftooh no. 101]
Translated by
Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan