Yahya related to me from Malik from Zayd ibn Aslam that theMessenger of Allah, may Allah bless him and grant him peace, said,"When you marry a woman or buy a slave-girl, take her by the forelockand ask for baraka. When you buy a camel, take the top of its hump,and seek refuge with Allah from Shaytan."
USC-MSA web (English) reference: Book 28, Hadith 52
Arabic reference: Book 28, Hadith 1147