Abu al-Zinad (may Allah have mercy on him) said that Umar bin Abd al-Aziz (may Allah have mercy on him) gave even a slave the eighty lashes of the prescribed punishment for slander.
Abu al-Zinad (may Allah have mercy on him) said: I asked Abdullah bin Amir bin Rabi'ah (may Allah be pleased with him) about this, and he said: I did not see Umar (may Allah be pleased with him), Uthman (may Allah be pleased with him) or the many other caliphs (may Allah be pleased with them) give more than forty lashes.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحدود / 17139