The Book of Marriage (Kitab Al-Nikah)
Muslim :: Book 8 : Hadith 3393
Judama bint Wahb al-Asadiyya (Allah be pleased with her) reported: I heard Allah's Messenger (may peace be upon him) saying this. The rest of the hadith is the same concerning 'azl and ghila (cohabitating with a suckling woman), but with a slight variation of words.