Ibn Jurayj said that Ibn `Abbas said that,

﴿فَأْذَنُواْ بِحَرْبٍ﴾

(then take a notice of war) means, "Be sure of a war from Allah and His Messenger.'' He also said, "On the Day of Resurrection, those who eat Riba will be told, `take up arms for war.''' He then recited,

﴿فَإِن لَّمْ تَفْعَلُواْ فَأْذَنُواْ بِحَرْبٍ مِّنَ اللَّهِ وَرَسُولِهِ﴾

(And if you do not do it, then take a notice of war from Allah and His Messenger.)

`Ali bin Abi Talhah said that Ibn `Abbas said about,

﴿فَإِن لَّمْ تَفْعَلُواْ فَأْذَنُواْ بِحَرْبٍ مِّنَ اللَّهِ وَرَسُولِهِ﴾

(And if you do not do it, then take a notice of war from Allah and His Messenger,) "Whoever kept dealing with Riba and did not refrain from it, then the Muslim Leader should require him to repent. If he still did not refrain from Riba, the Muslim Leader should cut off his head.''

Allah then said,

﴿وَإِن تُبتُمْ فَلَكُمْ رُءُوسُ أَمْوَلِكُمْ لاَ تَظْلِمُونَ﴾

(But if you repent, you shall have your capital sums. Deal not unjustly) by taking the Riba,

﴿وَلاَ تُظْلَمُونَ﴾

(And you shall not be dealt with unjustly) meaning, your original capital will not diminish. Rather, you will receive only what you lent without increase or decrease. Ibn Abi Hatim recorded that `Amr bin Al-Ahwas said, "The Messenger of Allah gave a speech during the Farewell Hajj saying;

«أَلَا إِنَّ كُلَّ رِبًا كَانَ فِي الْجَاهِلِيَّةِ، مَوْضُوعٌ عَنْكُمْ كُلُّهُ، لَكُمْ رُؤُوسُ أَمْوَالِكُم لَا تَظْلِمُونَ وَلَاتُظْلَمُونَ، وَأَوَّلُ رِبًا مَوْضُوعٍ، رِبَا الْعَبَّاسِ بْنِ عَبْدِالْمُطَّلِبِ مَوْضُوعٌ كُلُّه»

(Verily, every case of Riba from the Jahiliyyah is completely annulled. You will only take back your capital, without increase or decrease. The first Riba that I annul is the Riba of Al-`Abbas bin `Abdul-Muttalib, all of it is annulled.)