Quran 2:251 — The Heifer (Al-Baqarah)

They defeated them by GOD's leave, and David killed Goliath. GOD gave him kingship and wisdom, and taught him as He willed. If it were not for GOD's support of some people against others, there would be chaos on earth. But GOD showers His grace upon the people.

[2:250] When they faced Goliath and his troops, they prayed, "Our Lord, grant us steadfastness, strengthen our foothold, and support us against the disbelieving people."

[2:252] These are GOD's revelations. We recite them through you*, truthfully, for you are one of the messengers.