Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 68
Narrated 'Abdullah bin Zam'a:
The Prophet forbade laughing at a person who passes wind, and said, "How does anyone of you beat his wife as he beats the stallion camel and then he may embrace (sleep with) her?" And Hisham said, "As he beats his slave"