Musnad Ahmad 788:164

Yahya narrated to us, from al-Taymi, from Abu Uthman, from Abu Musa, who said: The people took a mountain pass or a steep path. Whenever a man ascended it, he would call out: "There is no god but Allah, and Allah is the Greatest." The Prophet, peace and blessings of Allah be upon him, was on a mule, inspecting the horses. He said: "O people, you are not calling upon one who is deaf, nor one who is absent." Then he said: "O Abu Musa—or O Abdullah ibn Qays—shall I not guide you to a treasure from the treasures of Paradise?" I said: "Yes." He said: "There is no power and no strength except by Allah."