It takes two to make a bargain.
Prov. Both parties in a negotiation must agree in order for the negotiation to be successful. Jill: You'll give me a ride to work every day this week, like we agreed, won't you? Jane: Wait a minute. I only said I'd give you a ride to work today. It takes two to make a bargain. Ellen: We decided you should make dinner tonight, right? Fred: No, we didn't decide that; you decided that. It takes two to make a bargain.