The Islamic economy depends on Shar`y (Islamically lawful) trade through investing money in ways that Allah (Exalted be He) made Halal (Lawful) according to the regulations of Shar`y dealings and transactions. This is based on the basic principle of permissibility as far as transactions are concerned, and abstaining from all that Allah (Exalted be He) prohibited, such as Riba (usury/interest). Allah (Exalted be He) says:
...whereas Allâh has permitted trading and forbidden Ribâ (usury).
And He (Exalted be He) says:
Then when the (Jumu‘ah) Salât (prayer) is ended, you may disperse through the land, and seek the Bounty of Allâh (by working, etc.), and remember Allâh much: that you may be successful.
(Part No. 13; Page No. 8)
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.