Musannaf Ibn Abi Shayba 19:152

Abu Bakr narrated to us, he said: Abd al-Rahim ibn Sulayman narrated to us, from Sufyan, from Abdullah ibn Dhakwan, from Abdullah ibn Amir ibn Rabi'ah, he said: Abu Bakr al-Siddiq, Umar ibn al-Khattab, and Uthman ibn Affan used to not flog the slave for false accusation (qadhf) more than forty [lashes]. Then I saw them increasing upon that.