Read the full text of Henry VI Part 3 Act 1 Scene 3 with a side-by-side translation HERE.
Rutland (York's youngest son) and his tutor are hanging out when they bump into Clifford and his soldiers.
Clifford pulls an Inigo Montoya again by saying your "father slew my father, he shall die."
The tutor says that Rutland is just an innocent child, so Clifford shouldn't harm him. Rutland begs for his life, too.
It doesn't do any good: Clifford says that because York killed his dad, he wants York to suffer, too—and he won't stop until all Yorks are dead.
Rutland begs for his life again and asks Clifford to take pity. Clifford stabs him, anyway.
Then Rutland utters something in Latin: "Di faciant laudis summa sit ista tuae." Translation: "May the gods cause your action to be that which makes you best known." Basically, Rutland is saying, "Go ahead and kill me, but that will be all you're known for." Well, that just gave us the chills.
Rutland dies, and Clifford is unfazed. Death to all Yorks! he yells as he runs off.