Listener question: The first agreement and clean questions

I really valued your two Podcasts last month on clean questions and have listened to them several times. 

I see a link between don Miguel Ruiz’s most important First Agreement; Be Impeccable With Your Word and Clean Language/Clean Coaching. 

Please can you expand further on what you mean by clean questions and where it originated? 

I am just about to order Radical Candor and I wondered how that ties in with clean questions too. 

Please can you share a further Podcast on this?