Maliks Muwatta Book 30, Hadith Number 16.

Yahya related to me from Malik that Muhammad ibn Abd ar-Rahman ibn Nawfal said, ”Urwa ibn az-Zubayr informed me from A’isha umm al-muminin that Judama bint Wahb al-Asadiyya informed her that she heard the Messenger of Allah, may Allah bless him and grant him peace, say, ‘I intended to prohibit ghila but I remembered that the Greeks and Persians do that without it causing any injury to their children.'” Malik explained, “Ghila is that a man has intercourse with his wife while she is suckling.”