And when Saul marched out with his army , he warned : " Allah is going to put you to a test by the side of a river : whoso drinks of its water shall cease to be my companion : he alone shall be ~ my companion who does not quench his thirst with its water : one may , however , take except a few , drank their fill of it . Afterwards when Saul , and those who had believed with him , crossed the river and advanced forward , the former said to Saul , " We have no power left this day to fight against Goliath and his hosts . "