“What's done cannot be undone.”
“What is done cannot be undone, but one can prevent it happening again.”
“What you have done to this point cannot be undone. What you do next... It is still unwritten.”
“What is done can never be undone.”
“The whole point of getting things done is knowing what to leave undone”
“[H]e began to understand what a wild game we play in life; he began to understand that a thing once done cannot be undone nor changed by saying "I am sorry!”