Sahih Bukhari Volume 005, Book 058, Hadith Number 124.

Narated By Sa'd's father : When the emigrants reached Medina. Allah's Apostle established the bond of fraternity between 'Abdur-Rahman and Sad bin Ar-Rabi. Sad said to 'Abdur-Rahman, "I am the richest of all the Ansar, so I want to divide my property (between us), and I have two wives, so see which of the two you like and tell me, so that I may divorce her, and when she finishes her prescribed period (i.e. 'Idda) of divorce, then marry her." Abdur-Rahman said, "May Allah bless your family and property for you; where is your market?" So they showed him the Qainuqa' market. (He went there and) returned with a profit in the form of dried yogurt and butter. He continued going (to the market) till one day he came, bearing the traces of yellow scent. The Prophet asked, "What is this (scent)?" He replied, "I got married." The Prophet asked, "How much Mahr did you give her?" He replied, "I gave her a date-stone of gold or a gold piece equal to the weight of a date-stone." (The narrator, Ibrahim, is in doubt as to which is correct.)