'Abdullah bin 'Amir bin Rabi'ah narrated, 'I witnessed the time of Abu Bakr, 'Umar and 'Uthman (RAA), and those who came after them. I never saw them flogging a slave for Qadhf (false accusation of adultery) except forty lashes.' Related by Malik, and Ath-Thawri in his book al-Jami.'
English reference: Book 10, Hadith 1265
Arabic reference: Book 10, Hadith 1226