1. The Lawful and Unlawful in Regards
Interest involving Business Transactions

2. Islam permits increase in capital through trade
Allah says,
“O you who believe, do not consume your property among yourselves wrongfully, but let there be trade by mutual consent....” (4:29)
At the same time, Islam blocks the way for anyone who tries to increase his capital through lending on usury or interest (riba), whether it is at a low or a high rate, reprimanding the Jews for taking usury, even though they had been prohibited to do so. Among the last revelations are the following verses of Surah al-Baqarah:
“O you who believe, fear Allah and give up what remains due to you of interest if you are indeed Believers. And if you do not, then be warned of war (against you) by Allah and His Messenger, while if you repent you shall have your capital. Do not do wrong and you shall not be wronged. “ (2: )

3. The Prophet declared war on usury and those who deal in it
He pointed out its dangers to society, saying,
“When usury and fornication appear in a community, the people of that community render themselves deserving of the punishment of Allah.”
(Hakim)
The strict prohibition of interest in Islam is a result of its deep concern for the moral, social, and economic welfare of mankind.

4. The dangers of Interest are many. Here are a few:
The taking of interest implies appropriating another person's property without giving him anything in exchange, because one who lends one dirham for two dirhams gets the extra dirham for nothing.
Now, a man's property is for (the purpose of) fulfilling his needs and it has great sanctity, according to the hadith,
'A man's property is as sacred as his blood'
(Transmitted by Abu Na'eem in Al-hilbah.)
This means that taking it from him without giving him something in exchange is haram.

5. Dependence on interest prevents people from working to earn money
Since the person with dirhams can earn an extra dirham through interest, either in advance or at a later date, He in turn will not work for it. The value of work will consequently be reduced in his estimation, and he will not bother to take the trouble of running a business or risking his money in trade or industry.
This will lead to depriving people of benefits, and the business of the world cannot go on without industries, trade and commerce, building and construction, all of which need capital at risk.

6. Permitting the taking of interest discourages people from doing good to one another, as is required by Islam
If interest is prohibited in a society, people will lend to each other with good will, expecting back no more than what they have loaned, while if interest is made permissible the needy person will be required to pay back more on loans (than he has borrowed), weakening his feelings of good will and friendliness toward the lender.
This causes moral decline

7. Finally the lender is very likely to be wealthy and the borrower poor
If interest is allowed, the rich will exploit the poor, and this is against the spirit of mercy and charity.
Thus, in a society in which interest is lawful, the strong benefit from the suffering of the weak. As a result, the rich become richer and the poor poorer, creating socio- economic classes in the society separated by wide gulfs.
Naturally this generates envy and hatred among the poor toward the rich, and contempt and callousness among the rich toward the poor. Conflicts arise, the socio- economic fabric is rent, revolutions are born, and social order is threatened.

8. Unquestionably the money-lender who takes interest, getting more from the borrower than his capital, is accursed in the sight of Allah and the people
But Islam, with its characteristic method of dealing with the haram, does not confine the sin to the lender on interest alone; it considers the borrower who pays him interest, the writer of the promissory note, and the witness to it to be among his accomplices. A hadith says:
“Allah has cursed the one who takes interest, the one who pays it, the one who writes the contract, and the one who witnesses the contract. “
(Reported by Ahmad, Abu Daoud, al-Nisai, Ibn Majah, and al-Tirmidhi)

9. However, if a person is driven to borrowing money on interest due to some pressing need, the sin will be on the lender alone. Now, to establish such a pressing need certain conditions must be met:
The need must be real, not merely an extension of the scope of one's needs and the desire for luxury. It must be so basic that life is not possible without it, for example, food, clothing, and medical treatment.
This concession is limited to the exact amount needed. Thus, for example, if nine dollars is sufficient, borrowing ten dollars is not lawful.
The borrower must continue to search for ways to escape from his predicament, and his brother Muslims should help him in this. If no other means are found, he can resort to borrowing on interest with no intention of liking it or transgressing the limits, and hope for forgiveness from Allah, as indeed He is Forgiving and Merciful.
He must continue to hate it and regret doing it until Allah opens a way out for him.