Musnad Ahmad 788:115

'Abd al-Wahhab ibn 'Abd al-Majid al-Thaqafi Abu Muhammad narrated to us, Khalid al-Hadhdha' narrated to us, from Abu 'Uthman al-Nahdi, from Abu Musa al-Ash'ari, who said: "We were with the Messenger of Allah (peace and blessings of Allah be upon him) on a military expedition. We would not ascend a high ground, nor climb a high place, nor descend into a valley, except that we raised our voices with the Takbir (saying 'Allahu Akbar'). The Messenger of Allah (peace and blessings of Allah be upon him) drew near to us and said: 'O people, be gentle with yourselves, for you are not calling upon one who is deaf or absent; you are only calling upon One who is All-Hearing, All-Seeing. Indeed, the One whom you call upon is closer to one of you than the neck of his riding beast.' 'O 'Abdullah ibn Qays, shall I not teach you a word from the treasures of Paradise? [It is]: La hawla wa la quwwata illa billah (There is no power and no strength except by Allah).'"