The Bible has 14 references to someone tearing his clothes...though not with the word 'off'. It was a sign of despair, mourning etc and was usually followed by the person wearing sackcloth and ashes.
You don't actually ask a question, so I am unsure precisely what it is you want to know.
Thank you Quizmonster, you have answered my question as to what the phrase: "and he tore his clothes" means. If I understand you correctly it means a sign of despair.