It is disliked to trade with one whose wealth is mostly from usury or the price of unlawful things

Sayyiduna Nu'man bin Bashir (may Allah be pleased with them both) said, and (the narrator said:) by Allah, I will never hear anyone after him say it: I heard the Messenger of Allah (peace and blessings be upon him) say: "The lawful is clear and the unlawful is clear, and what is between them is doubtful." And sometimes he said: "doubtful matters. I will soon give you an example: Allah, the Lord of Might, has set up a protected pasture, and Allah's protected pasture is what He has made unlawful; and whoever grazes (his animals) around the protected pasture is close to entering the pasture." The narrator said: Sometimes he said: "is close to grazing in it; and whoever gets involved in what is doubtful is close to becoming bold." The narrator said: I do not know whether this is part of the hadith or something that al-Sha'bi said.

Sayyiduna Nu'man bin Bashir (may Allah be pleased with him) was saying on the pulpit: I heard the Messenger of Allah (peace and blessings be upon him) say: "The lawful is clear and the unlawful is clear, and between them are doubtful things. Whoever leaves the sin that is doubtful to him will all the more leave what is clear to him; and whoever ventures upon what he is in doubt about is close to falling into the unlawful. Indeed, every king has a protected pasture, and Allah's protected pasture on earth is the acts of disobedience to Him."

Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "I return to my family and find a date fallen on my bed or in my house, and I pick it up to eat it, but then I fear that it may be from the charity (sadaqah), so I throw it away."

Abu al-Hawra' says: I said to Hasan bin Ali (may Allah be pleased with them both): Do you remember anything from the Prophet (peace and blessings be upon him)? He said that he (peace and blessings be upon him) used to say: "Leave what makes you doubt for what does not make you doubt, for truthfulness brings tranquillity, while falsehood brings doubt."

Sayyiduna Atiyyah al-Sa'di (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "A servant cannot attain the rank of the righteous until he keeps away from harmless things, and all the more so leaves harmful things."

Humayd bin Hilal (may Allah have mercy on him) narrates from a Bedouin of his people (may Allah be pleased with him) that he said: I came to the Messenger of Allah (peace and blessings be upon him) while he was delivering a sermon, and I said: O Messenger of Allah! Teach me. At the end of what I memorised was that he (peace and blessings be upon him) said: "Whenever you leave something out of fear of Allah, Allah gives you in its place something better than it."

Abu Hamzah Imran bin Abi Ata (may Allah have mercy on him) says: I said to Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): My father is a dealer in goats and sheep, and he is in partnership with Jews and Christians. Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: We do not go into partnership with a Jew, a Christian or a Magian. I said: Why? (He said:) Because they take usury (riba), and usury is not permissible.

Rabi' bin Abdullah heard a man ask Ibn Umar (may Allah be pleased with them both): Our neighbour consumes usury (riba), or his earnings are unlawful, and sometimes he invites me to a meal; should I accept? He said: Yes.

Harith bin Suwayd says that a man came to Abdullah bin Mas'ud (may Allah be pleased with him) and said: I have a neighbour, and all I know of his earnings is that they are unlawful or impure. He invites me to eat with him, but I feel it is wrong to go to him, and I also feel uneasy about not going. He said: Accept his invitation; his sin is upon him.
Note: This applies when he does not know that what has been served to him is unlawful; but when he knows that it is unlawful, he should not eat it, just as the Messenger of Allah (peace and blessings be upon him) refused to eat the goat.
Jawwab al-Taymi is not strong.

Asim bin Kulayb narrates from his father, and he from a man of the Ansar (may Allah be pleased with him), that he said: We went out with the Prophet (peace and blessings be upon him) for a funeral. I saw the Messenger of Allah (peace and blessings be upon him) instructing the grave-digger: "Widen it on the side of the feet and the head." When he (peace and blessings be upon him) returned, a woman invited him. He (peace and blessings be upon him) came, the food was brought, he (peace and blessings be upon him) put his hand in the food, and the people also began eating. Our fathers saw the Messenger of Allah (peace and blessings be upon him) chewing a morsel in his mouth; then he (peace and blessings be upon him) said: "This is the meat of a goat that has been taken without the permission of its owner." The woman said: O Messenger of Allah! I sent someone to al-Baqi' to buy a goat, but none was found. Then I sent someone to my neighbour asking him to provide a goat for its price, but it could not be had. Then I sent someone to his wife, and she brought the goat. He (peace and blessings be upon him) said: "Feed (this food) to the captives."

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him): "Whoever buys stolen property, knowing that it is stolen, is an equal partner in its disgrace and sin."