Why did Prophet Muhammad (peace be upon him) ask 'Abdur-Rahman bin `Auf what Mahr he had given to the Ansari woman he had married?
 Narrated Anas:                     When `Abdur-Rahman bin `Auf married an Ansari woman, the Prophet asked him, "How much Mahr did you give her?" `Abdur-Rahman said, "Gold equal to the weight of a date stone." Anas added: When they (i.e. the Prophet and his companions) arrived at Medina, the emigrants stayed at the Ansar's houses. `Abdur-Rahman bin `Auf stayed at Sa`d bin Ar-Rabi's house. Sa`d said to `Abdur- Rahman, "I will divide and share my property with you and will give one of my two wives to you." `Abdur-Rahman said, "May Allah bless you, your wives and property (I am not in need of that; but kindly show me the way to the market)." So `Abdur-Rahman went to the market and traded there gaining a profit of some dried yoghurt and butter, and married (an Ansari woman). The Prophet said to him, "Give a banquet, even if with one sheep."