The worst form of usury is attacking the honour of a Muslim man

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Usury (riba) has seventy-three doors; the lightest of them is like a man marrying (committing indecency with) his own mother, and the greatest usury is to go after the honour of a Muslim man."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and they did not record it.

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "There are four kinds of people whom Allah has made it binding upon Himself not to admit into Paradise nor let them taste its blessings: the habitual drinker of wine, the one who consumes usury (riba), the one who consumes the wealth of an orphan unjustly, and the one who is disobedient to his parents."
This hadith has an authentic chain (sahih al-isnad), but the two Shaykhs (Bukhari and Muslim) did not record it, although they both agreed on the reliability of the narrator Khuthaym.