Whoever curses the three Sahabah contradicts the Qur'an and the Sunnah
How to deal with someone who curses the three Sahabah?
A: The Sahabah (Companions) of the Prophet (peace be upon him) were the best generation of this Ummah (nation), and Allah (Exalted be He) praises them in His Book saying:
And the foremost to embrace Islâm of the Muhâjirûn (those who migrated from Makkah to Al-Madinah) and the Ansâr (the citizens of Al-Madinah who helped and gave aid to the Muhâjirûn ) and also those who followed them exactly (in Faith). Allâh is well-pleased with them as they are well-pleased with Him. He has prepared for them Gardens under which rivers flow (Paradise), to dwell therein forever. That is the supreme success.
Indeed, Allâh was pleased with the believers when they gave the Bai‘ah (pledge) to you (O Muhammad صلى الله عليه وسلم) under the tree: He knew what was in their hearts, and He sent down As-Sakînah (calmness and tranquility) upon them, and He rewarded them with a near victory.
There are many other Ayahs (Qur'anic verses) in which Allah praises the Sahabah and promises them Jannah (Paradise).
`Aly were among the first to embrace Islam and among those who gave Bay`ah (the pledge of allegiance) to the Prophet (peace be upon him) under the tree. The Prophet (peace be upon him) gave himself the Bay`ah (Part No. 3; Page No. 399) on behalf of
`Uthman, as he was absent. This was a testimonial to his trust in `Uthman, and a stronger Bay`ah than those the others gave to him (peace be upon him). The Prophet praised them in many Hadiths, in general and in particular, especially
`Aly. He gave them the good news of Jannah, along with a group of his Sahabah, and he warned against cursing them when he said,
"Do not curse my Sahabah, because if any of you spent gold equal to (Mount) Uhud (in Allah's Cause), it would not be equal to a Mud (a dry measure of half bushel, 543 grams) or even a half Mud of one of them."
Muslim in his "Sahih [Book of Authentic Hadith] on the authority of
Abu Hurayrah and
Abu Sa`id Al-Khudry).
So anyone who curses or reviles the Sahabah of the Prophet (peace be upon him), especially one of the three:
`Uthman who were mentioned in the question, has contradicted the Book of Allah and the Sunnah of the Messenger. They will be faced with their vilification and they will be deprived of the forgiveness that Allah promised those who came after them and asked forgiveness for them and supplicated to Allah not to let there be any malice in His Heart against the believers. They should be advised against their vilification of these three Companions and others like them, and their attention should be drawn to their virtues, status, and their honest stances in Islam. If they perform Tawbah (repentance to Allah), they are brothers in Islam, but if they persist in cursing them, they should be prevented from doing so by utilizing the Islamic legal policy of changing the detestable by the possible means. Those who are unable to change it by their hands or tongues should despise it in their hearts, and this is the weakest form of Iman (belief), as was authentically reported in a Sahih (a Hadith that has been transmitted by people known for their uprightness and exactitude; free from eccentricity and blemish) Hadith.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.