Sahih Bukhari Volume 008, Book 075, Hadith Number 395.

Narated By Anas : The Prophet seeing a yellow mark (of perfume) on the clothes of 'Abdur-Rahman bin 'Auf, said, "What about you?" 'Abdur-Rahman replied, "I have married a woman with a Mahr of gold equal to a date-stone." The Prophet said, "May Allah bestow His Blessing on you (in your marriage). Give a wedding banquet, (Walima) even with one sheep."