After George reprimands him, Lennie offers to go away in a cave. What is George's response?

From the text:

“No—look! I was jus’ foolin’, Lennie. ‘Cause I want you to stay with me. Trouble with mice is you always kill ‘em.” He paused. “Tell you what I’ll do, Lennie. First chance I get I’ll give you a pup. Maybe you wouldn’t kill it. That’d be better than mice. And you could pet it harder.”