Qur’aan
Allah, may He be exalted, says (interpretation of the meaning):
“ Those who consume interest cannot stand [on the Day of Resurrection] except as one stands who is being beaten by Satan into insanity. That is because they say, ‘Trade is [just] like interest.’ But Allah has permitted trade and has forbidden interest. So whoever has received an admonition from his Lord and desists may have what is past, and his affair rests with Allah. But whoever returns to [dealing in interest or usury] – those are the companions of the Fire; they will abide eternally therein.
Allah destroys interest and gives increase for charities. And Allah does not like every sinning disbeliever.
Indeed, those who believe and do righteous deeds and establish prayer and give zakah will have their reward with their Lord, and there will be no fear concerning them, nor will they grieve.
O you who have believed, fear Allah and give up what remains [due to you] of interest, if you should be believers.
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”
[al-Baqarah 2:275-279].
Ahadith
Abu Huraira reported: The Prophet, peace and blessings be upon him, said, “ Stay away from seven mortal sins.” They said, “O Messenger of Allah, what are they?” The Prophet said, “Idolatry with Allah, occult magic, killing a soul that Allah has sanctified except for a just cause, consuming usury , usurping the property of an orphan, fleeing the battlefield, and accusing chaste but unwary believing women.”
(Ṣaḥīḥ al-Bukhārī 6465, Ṣaḥīḥ Muslim 89)
Al-Tabari reported: Ibn Abbas, may Allah be pleased with him, said, “ It will be said on the Day of Resurrection to those who consumed usury: Take your weapon for war!” Then he recited the verse, “ Those who consume usury cannot stand but as one stands who is being beaten by Satan into insanity.” (2:275)
(Tafsīr al-Ṭabarī 2:279 (Sahih))
Abdullah ibn Mas’ud reported: The Messenger of Allah, peace and blessings be upon him, said, “ Adultery and usury do not become prevalent among people but that the punishment of Allah Almighty is justified against them .”(Ṣaḥīḥ Ibn Ḥibbān 4502)
Abdullah ibn Mas’ud reported: The Prophet, peace and blessings be upon him, said, “ Allah has cursed the one who consumes usury, its client, its witness, and its recorder. Usury and adultery do not become widespread among people but that they will become vulnerable to the punishment of Allah Almighty. ”(Musnad Aḥmad 3799)
Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said, “ A time will come upon people in which they will consume usury.” It was said, “All of the people?” The Prophet said, “ Whoever does not consume it will be affected by its dust.” (Musnad Aḥmad 10191)
It was narrated that Jaabir said: The Messenger of Allah (peace and blessings of Allah be upon him) cursed the one who consumes riba and the one who pays it, the one who writes it down and the two who witness it, and he said: they are all the same.
Narrated by Muslim (1598).
The Prophet (peace and blessings of Allaah be upon him) said: “ A dirham which a man consumes as riba knowingly is worse before Allaah than thirty-six acts of zina.” (Narrated by Ahmad and al-Tabaraani)
And he said: “ There are seventy-two types of riba, the least of which is like a man committing incest with his mother. ” (Narrated by al-Tabaraani)
Al-Bukhaari (1386, 7047) narrated that Samurah ibn Jundub said:
The Messenger of Allaah (peace and blessings of Allaah be upon him) often used to ask his companions, “ Has any one of you had a dream?” Then those whom Allaah willed would tell him (about their dreams). One morning he said, “Last night, two people came to me (in a dream), and woke me up and said, ‘Let’s go!’ I set out with them, and we came across a man who was lying down, with another man standing over him, holding a big rock. He threw the rock at the man’s head, smashing it. The rock rolled away, and the one who had thrown it followed it, and picked it up. By the time he came back to the man, his head had been restored to its former state. Then he (the one who had thrown the rock) did the same as he had done before. I said to my two companions, ‘Subhaan Allaah! Who are these two persons?’ They said, ‘Move on!’
So we went on, and came to a man who was lying flat on his back, with another man standing over him, holding an iron hook. He put the hook in the man’s mouth and tore off that side of his face to the back (of his neck), and he tore his nose and his eye from front to back in a similar manner. Then he turned to the other side of the man’s face and did likewise. No sooner had he finished the second side but the first side was restored to its former state, then he went back and did the same thing again. I said to my two companions, ‘Subhaan Allaah! Who are these two persons?’ They said, ‘Move on!’
So we went on, and came to something like a tannoor (a kind of oven, lined with clay, usually used for baking bread).” (I think the Prophet (peace and blessings of Allaah be upon him) said, in that oven there was much noise and voices. The Prophet (peace and blessings of Allaah be upon him) added:) “We looked into it and saw naked men and women. A flame of fire was reaching them from underneath, and when it reached them, they cried out loudly. I asked them, ‘Who are these?’ They said to me, ‘Move on!’
So we went on and came to a river. (I think he said, red like blood.) In the river there was a man swimming, and on the bank there was a man who had gathered many stones. Whilst the swimmer was swimming, the man who had gathered the stones approached him. The swimmer opened his mouth and the man on the bank threw a stone into it, then the swimmer carried on swimming. Each time he came back, he opened his mouth again, and the man on the bank threw another stone into his mouth. I said to my two companions, ‘Who are these two persons?’ They said, ‘Move on, move on!’
I said to them, “I have seen many wonders this night. What do all these things mean that I have seen?’ They said, ‘We will tell you.
The first man you came across, whose head was being smashed with the rock, is the man who studies the Qur’aan, then he neither recites it nor acts upon it, and he goes to sleep, neglecting the obligatory prayers.
The (second) man you came across whose mouth, nose and ears were being torn from front to back, is the man who goes out of his house in the morning and tells a lie that is so serious that it spreads all over the world.
The naked men and women whom you saw in a structure that resembled an oven are the adulterers and adulteresses.
The man you saw swimming in the river with rocks being thrown into his mouth is the one who consumed riba (usury). ”
Interest and Usury have almost the same meaning in our context, Riba is the arabic word for interest.