2-Surah Al-Baqarah ( The Cow ) 279
And if you do not, then be informed of a war [against you] from Allah and His Messenger. But if you repent, you may have your principal – [thus] you do no wrong, nor are you wronged.
فَإِن لَّمْ تَفْعَلُوا فَأْذَنُوا بِحَرْبٍ مِّنَ اللَّهِ وَرَسُولِهِ ۖ وَإِن تُبْتُمْ فَلَكُمْ رُءُوسُ أَمْوَالِكُمْ لَا تَظْلِمُونَ وَلَا تُظْلَمُونَ
Quran's Tafhim ( explanation)
*323). This verse was revealed after the conquest of Makka and has been placed here because of its contextual relevance. Although interest was considered objectionable earlier, it had not been legally prohibited. After the revelation of this verse interest-bearing transactions became a punishable offence within the realm of Islam. The Prophet (peace he on him) warned the Arab tribes through his officials that war would be declared against them if they did not give up interest-bearing transactions. It was specified, for instance, in the agreement under which the Christians of Najran were granted internal autonomy under the suzerainty of the Islamic state, that if they continued to use interest, the agreement with them would be considered void and their action an act of belligerency. On the basis of the last words of the verse, Ibn 'Abbas, Hasan al-Baari, Ibn Sirin and Rabi' ibn Anas are of the view that anyone who takes interest within the boundaries of the Islamic State (Dar al-Islam) should be pressed to repudiate the transaction and recant and, if he persists, should be put to death. Others consider it sufficient to imprison such people and keep them in prison until they pledge to give up taking interest. (See Jassas's commentary, on verse 2: 278; see especially vol. 1, pp. 471 f. - Ed.)