Musannaf Ibn Abi Shayba 19:801

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Sadaqah ibn ‘Abd Allah, from al-Harith ibn ‘Utbah, that a man was brought to ‘Umar ibn ‘Abd al-‘Aziz who was insulting ‘Uthman. He said: "What drove you to insult him?" He said: "I hate him." He said: "And if you hate a man, do you insult him?" He said: So he ordered him to be whipped thirty lashes.