No. It's more prejudicial than probative in this case. All that matters is what went down. Not what he said in the past. Either he had a right to defend or he didn't. Saying "I'm going to walk through Harlem and if someone tries to kill me, I'll defend myself by killing them," and then walking through Harlem, getting attacked, and killing the guy, doesn't somehow turn the statement into evidence of intent to murder.