It was a huge demand, for he was rich. Went away grieved. He felt that Jesus had asked too much of him. He worshipped money more than God when put to the test. Not unless he is in the grip of money.
Different persons are in the power of different sins.
One sin is enough to keep one away from Christ. Jesus, of course, means by this comparison, whether an eastern proverb or not, to express the impossible. But the Koran may have got this figure from the New Testament. Imperfect descriptive of their blank amazement. Jesus saw their amazement.