Maliks Muwatta Book 20, Hadith Number 19.

Yahya related to me from Malik from Nafi from Aslam, the mawla of Umar ibn al Khattab, that Umar ibn al-Khattab discovered the smell of perfume while he was at ash-Shajara, and he asked, “Who is this smell of perfume coming from?” Muawiya ibn Abi Sufyan answered, “From me, amir al-muminin.” Umar said, “From you? By the life of Allah!” Muawiya explained, “Umm Habiba perfumed me, amir al-muminin. “‘Umar then said, “You must go back and wash it off.”