Who said "We have to act as if he is still alive."?

This quote is attributed to Michael Corleone.

We have to act as if he is still alive. - Michael Corleone

"We have to act as if he is still alive."

Michael Corleone

"I'm gonna make him an offer he can't refuse."

"It's not personal, Sonny. It's strictly business."

"A man who doesn't spend time with his family can never be a real man."

"The things you own end up owning you."