“Reward is in proportion to the intelligence (wisdom) of a person"

It is recorded in reliable sources that a man went to Imam as-Sadiq and began to praise someone’s worshipping and religiousness. Imam asked: How much intelligence does he have? He said he did know that. Then Imam said, “Reward is in proportion to the intelligence (wisdom) of a person. There was a great worshipper in The Israelites. He spent all his time worshipping on an island. It was a very fertile island with clean water springs and fruitful trees. Once an angel passed by that man. The angel was very pleased with his worship and he prayed to Allah: My Lord! Please let me know the reward of this man’s worshipping. Allah told the angel what he thought was that man’s reward. The angel felt that the reward was much less compared to his worship. So Allah asked that angel to go and live with that worshipper for a while. The angel went to that person in the form of a man. The worshipper asked him: Who are you? He replied, “I am also a worshipper like you. When I learned about this place and heard your praise I thought of coming here and worshipping along with you.”
Next morning the angel said to the man, “Your house is very spacious and very suitable for worship.” He said, “There is a defect in it.” “What is it?” the angel asked. He replied, “My Allah does not have a donkey of His own. Had He one He would have made it graze here so that this grass might not go to waste.” The angel told him that Allah does not require an ass. The worshipper replied, “Had He a donkey this grass would not have wasted.” Allah revealed to the angel, “I have fixed the reward of this man’s deed proportionate to his wisdom.”

Reference: Hayat Al-Qulub, Vol. 1, Stories of the Prophets