"Thieves Will Out"

Charge: murder in the first degree. M.O.: shotgun blast in the face. Defense: alibi. At D's trial the government calls W to testify that just before the shooting, the victim, V, handed him a slip of paper with D's nickname and telephone number on it. V told W to call the police if V were not home by 3 p.m. the next day and give the police the slip of paper. D objects to W's proposed testimony and to the introduction of the slip of paper. What ruling and why? Would the case for admission be stronger or weaker if the defense were self-defense or accident?