Why was Pharaoh so stubborn about setting the captives free?

Please and thanks!

5 answers

It has to do with the ten plagues.
http://video.aol.com/video-detail/the-stubborn-old-pharaoh-colbys-clubhouse-song-start-17sec-in/2283519013

http://bible.cc/exodus/11-10.htm
She had to poop badly
because
it is because the pharaoh’s heart was hardened