That scene is very revealing. When Vito asks, "Do you trust my judgment?" Clemenza answers, fervently, "Always, Godfather." Tessio just hisses, "Yesssss..." And Tess gives the left-handed handshake. Treason will out!
Ntra la porta tua lu sangu � sparsu, E nun me mporta si ce muoru accisu... E s'iddu muoru e vaju mparadisu Si nun ce truovo a ttia, mancu ce trasu.