Taking money without its owner's permission

Q 2: A man gave me a sum of two thousand riyals (Part No. 14; Page No. 72) to buy him a medicine from a healer. However, I bought the medicine for only one thousand and five hundred riyals and I kept the rest of the money. Is this Halal (lawful)? Provide us with your beneficial answer. May Allah reward you with all the best.

A: The sum of money, whether little or much, that remained after buying the medicine is the right of its owner who asked you to buy the medicine. It is Haram for you to take this money without first asking the permission and approval of its owner. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.