Musannaf Ibn Abi Shayba 3:6086

Ibn Fudayl and Abu Mu'awiyah narrated to us, from 'Asim, from Abu 'Uthman, from Abu Musa, who said: We were with the Prophet, may Allah bless him and grant him peace, on a journey, and the people began to raise their voices with the *takbir*. The Prophet, may Allah bless him and grant him peace, said: "O people, be gentle with yourselves. You are not calling upon one who is deaf, nor one who is absent. Indeed, you are calling upon One who is All-Hearing, Near, and He is with you."