Yahya related to me from Malik that Ibn Shihab used to say, "Wuduis necessary if a man kisses his wife." Nafi said that Malik said,"That is what I like most out of what I have heard." (RU)
USC-MSA web (English) reference: Book 2, Hadith 68 (RU)
Arabic reference (RU): Book 2, Hadith 98 (RU)