Quran Chapter 2 Verse 249-252
And when Saul went forth with the soldiers, he said, “Indeed, Allah will be testing you with a river. So whoever drinks from it is not of me, and whoever does not taste it is indeed of me, excepting one who takes [from it] in the hollow of his hand.” But they drank from it, except a [very] few of them. Then when he had crossed it along with those who believed with him, they said, “There is no power for us today against Goliath and his soldiers.” But those who were certain that they would meet Allah said, “How many a small company has overcome a large company by permission of Allah . And Allah is with the patient.”
And when they went forth to [face] Goliath and his soldiers, they said, “Our Lord, pour upon us patience and plant firmly our feet and give us victory over the disbelieving people.”
So they defeated them by permission of Allah , and David killed Goliath, and Allah gave him the kingship and prophethood and taught him from that which He willed. And if it were not for Allah checking [some] people by means of others, the earth would have been corrupted, but Allah is full of bounty to the worlds.
These are the verses of Allah which We recite to you, [O Muhammad], in truth. And indeed, you are from among the messengers.