In this verse, the Quran describes the king Saul (Talut) leading his army against Goliath. It claims that Saul tested his soldiers by telling them not to drink from a river, and only those who scooped a handful of water were chosen.
This event never happened to Saul.
Surah 2:249:
And when Saul set out with the army, he said: Lo! Allah will try you by (the ordeal of) a river. Whosoever therefore drinketh thereof he is not of me, and whosoever tasteth it not he is of me, save him who taketh (thereof) in the hollow of his hand. But they drank thereof, all save a few of them. And after he had crossed (the river), he and those who believed with him, they said: We have no power this day against Goliath and his hosts. But those who knew that they would meet Allah exclaimed: How many a little company hath overcome a mighty host by Allah's leave! Allah is with the steadfast.
In the Bible, this specific "lapping water" test was given by God to Gideon, who lived roughly 100 years BEFORE Saul.
Judges 5-7:
So Gideon took the men down to the water. There the Lord told him, “Separate those who lap the water with their tongues as a dog laps from those who kneel down to drink.”
Three hundred of them drank from cupped hands, lapping like dogs. All the rest got down on their knees to drink.
The Lord said to Gideon, “With the three hundred men that lapped I will save you and give the Midianites into your hands. Let all the others go home.”
The "eternal" author of the Quran seemingly confused the stories of TWO DIFFERENT leaders. If the Quran were divine, it would not attribute the biography of Gideon to Saul.