Sayyiduna Suhayb (may Allah be pleased with him) says: The Messenger of Allah (peace and blessings be upon him) would move his lips, but we could not understand it. We said: O Messenger of Allah (peace and blessings be upon him), you move your lips with something, but we cannot understand it. He (peace and blessings be upon him) said: "One of the prophets (peace and blessings be upon him) was pleased by the great number of his people, and he said: Who could stand against these? He said: It was said to him: Give your companions a choice: either We set an enemy over them who will destroy their community, or hunger, or death. He gave them the choice, and they chose death, and within three days seventy thousand men died." Then the Messenger of Allah (peace and blessings be upon him) said: "As for me, I say: 'Allahumma bika uqatilu, wa bika uhawilu, wa bika usawilu, wa la hawla wa la quwwata illa bika' (O Allah, with Your help I fight, by Your enabling I plan my affairs, and by Your enabling I contend; and the power to turn from evil and the strength to do good come only through Your enabling)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18464