Is it permissible for me to take used gold from (Part No. 13; Page No. 495) my friends and relatives to sell
in the gold market on their behalf and try to get them the best prices depending on my experience in this field? Is this prohibited pursuant to the Hadith stating that a city dweller should not sell a commodity on behalf of a desert dweller, to leave everyone profit as Allah wills them to? Similarly, is it permissible to buy on behalf of a friend or relative to get them the best price? All of this I do without a return, only hoping for the Reward of Allah.
It is permissible for you to take gold from your friend and sell it on his behalf. This is not the prohibited case of a city dweller selling on behalf of a desert dweller; rather, this is a favor you do to your friend such as advising them, fulfilling their needs, and buying for them.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his Family, and Companions.