Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) had the prescribed punishment applied to one of his slave women, and he said to the one who was flogging her: "Strike below both legs, and lightly." So we said: Then what is (the meaning of) this saying of Allah: "And let not pity for them take hold of you in the religion of Allah" [Surah al-Nur: 2]? He said: "Should I then kill her?"
Imam al-Shafi'i (may Allah have mercy on him) said: The Ansar and those (who came) after them used to apply the prescribed punishment to their slaves.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحدود / 17109