Musannaf Ibn Abi Shaybah

Hazrat Harith bin Utbah narrates that a man was brought to Hazrat Umar bin Abdul Aziz who used to abuse Hazrat Usman. He asked, "What made you abuse him?" He replied, "I bear enmity towards him." He said, "If you bear enmity towards someone, does that mean you should abuse him?" So, by his order, the man was given thirty lashes.