Abdullah bin Umar reported,

The Messenger of Allah ﷺ secluded himself in the mosque during the last ten days of Ramadan, and a small enclosure made of palm fronds was set up for him there. One day he put his head out and said, "The one who prays is in intimate conversation with his Lord , so let each of you consider what he is saying privately to his Lord, and let none of you raise his voice over another in recitation."

حدثنا عتاب حدثنا أبو حمزة يعني السكري عن ابن أبي ليلى عن صدقة المكي

عن ابن عمر قال

اعتكف رسول الله ﷺ في العشر الأواخر من رمضان فاتخذ له فيه بيت من سعف قال فأخرج رأسه ذات يوم فقال إن المصلي يناجي ربه عز وجل فلينظر أحدكم بما يناجي ربه ولا يجهر بعضكم على بعض بالقراءة