Prophet Muhammad ﷺ said:
إِنَّ اللَّهَ قَالَ مَنْ عَادَى لِي وَلِيًّا فَقَدْ آذَنْتُهُ بِالْحَرْبِ
Verily Allah ta’ala has said: ‘Whosoever shows enmity to a wali (friend) of Mine, then I have declared war against him.
[Sahih Bukhari]
Thiqa Tabai Abu Nadhra al Mundhir ibn Malik رحمہ اللہ said:
قَالَ كُنَّا بِالْمَدِينَةِ فسب رجل عُثْمَان فنهيناه فَلم ينْتَه فارعدت ثمَّ جَاءَت صَاعِقَة فَأَحْرَقتهُ
We were in Madinah when a man started abusing Saydna Usman and we tried to stop him, but he didn't stop. Then a lightning struck him and burned him.
[Kitab al Thiqat By Imam Ibn Hibban 7/105, Tarikh Damishq 29/511 sanad Hasan]
To'ama ibn Amr said: There was a man who became weak and weary from worship, he was asked "what happened to you"?
He said: I had sworn that I'll slap Uthman ibn Affan and when he was martyred, I went to him and slapped him. His wife (Nayla bint al Furafisa) cursed me saying:
أَشَلَّ اللَّهُ يَمِينَكَ، وَصَلَّى وَجْهَكَ النَّارَ
"May Allah paralyse your hand and burn your face in hellfire. Now, my hand is paralysed and I am living in fear of that second curse.
[Mujab ad Dawah, Imam ibn Abi dunya #30]
Imam al Aasim al Ahwal رحمہ اللہ who also appointed as judge (Qadhi) in maiden city said:
أتيت بِرَجُل قد سبّ عُثْمان فضربته عشرَة أسواط قالَ ثمَّ عاد لما ضَربته فضربته عشرَة أُخْرى فَلم يزل يسبه حَتّى ضَربته سبعين سَوْطًا
A man brought before me, who said ill things and reviled Saydna Usman رضیﷲ عنه, I whipped him 10 lashes, then he abused again and I whipped him with 20 lashes more and he continued to do the sams until I whipped him with 70 lashes.
[al ilal Maarifat ar Rijal la Ahmad 1/428 sanad sahih]
Imam Yahya ibn Ma'yeen رحمہ اللہ said regarding the Rafidhi Koofi Taleed bin Sulayman Muharbi:
تليد كَذّاب كانَ يشْتم عُثْمان وكل من يشْتم عُثْمان أو طَلْحَة أو أحدا من أصْحاب النَّبِي ﷺ دجال لا يكْتب عَنهُ وعَلِيهِ لعنة الله والمَلائِكَة والنّاس أجْمَعِينَ
He was a liar, he used to abuse Usman رضیﷲ عنه, anyone who abuse Saydna Usman, Saydna Talha or any companion of prophet Mohammad ﷺ ,is a Dajjal. No hadith will be taken from him, and curse of Allah, his angels and whole humanity be upon him.
[Tarikh ibn Ma'yeen ba riwayah ad Da'ori 3/546]
This same Taleed bin Sulayman Rafidhi was sitting on the roof with some people, and when Usman رضیﷲ عنه was mentioned he started to revile him, a man pushed him off the roof and broke his leg and due to this he became crippled from his leg and he used to walk with crutches for the rest of his life
[Tarikh ibn Ma'yeen ba riwayah ad Da'ori 3/285]