Show Me The Money

The Alabama legislature is in the process of passing a ban on same sex marriage. The bill has already passed in the Senate and is now in the House for debate. There is little doubt that the bill will pass. What I find interesting is one state representative is offering $5000 to anyone who can show him anywhere in the Bible that it says marriage is ONLY between a man and a woman. It started out with an offer of $700 then he raised it. He says he's certain he won't be losing his money. How about it folks? Can anyone show proof that there is a passage that states clearly that marriage is ONLY between a man and a woman? I'm pretty good with the Bible and I can't find one. Can you?
Keep in mind that the usage of the words husband and wife are not accepted as proof. Because even in same sex marriages one parter is the husband and one is the wife. Making the words themselves non-gender specific.