What do i tell my friend? He just lost his mother to cancer?

His mom fought for a while, but they had to "pull the plug" so she wouldn't suffer any longer.I would like to console him. But i know that he is very sensitive right now, so i want to be really careful with what i say. The thought of losing my mom is just unfathomable. It brings me to tears just thinking about it, I can't imagine how he feels like right now.