Sahih Bukhari Volume 007, Book 062, Hadith Number 172.
Narrated By Jabir : I was with Allah's Apostle in a Ghazwa, and when we returned, I wanted to hurry, while riding a slow camel. A rider came behind me. I looked back and saw that the rider was Allah's Apostle. He said (to me), "What makes you in such a hurry?" I replied, "I am newly married." He said, "Did you marry a virgin or a matron?" I replied, "(Not a virgin but) a matron." He said, "Why didn't you marry a young girl with whom you could play and who could play with you?" Then when we approached (Medina) and were going to enter (it), the Prophet said, "Wait till you enter (your homes) at night (in the first part of the night) so that the ladies with unkempt hair may comb their hair, and those whose husbands have been absent (for a long time) may shave their pubic hair." (The sub-narrator, Hashim said: A reliable narrator told me that the Prophet added in this Hadith: "(Seek to beget) children! Children, O Jabir!")