Answer
(Fatwa: 1804/B=409/TB=1433)
Commodity trading i.e. purchasing and selling of goods in exchange of goods is right, it is also right with difference, with good and bad, and in cash and on debt. However, purchasing and selling of gold with gold, silver with silver, wheat with wheat, barley with barley, dates with dates and salt with salt is lawful only when the weight of both the sides is equal, it is not lawful with difference. Also it is not lawful to sell and purchase on debt. You can sell in the evening after buying in the morning. You can make investment provided it is on the principles of Shariah. If you do brokerage and fix the charge in advance and do some hard work for the job and do not do deception and cheating then your income will be halal and lawful.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband