Just say a simple, ‘Yes, I will,’ or ‘No, I won’t.’ Anything beyond this is from the evil one.
Your heart and your words must agree for faith to work. Often believers will say one thing and then do something else. If you are not true to your word this will affect your faith. When you speak in faith you must believe in your heart that what you say is in fact already so, for you believe you receive when you pray (Mark11:24). So when someone consistently says one thing but yet they do something else, their heart doesn’t know whether to believe what they say is true or not. Make sure your yes means yes and your no means no, for it will affect your hearts ability to believe, for as Jesus said all things are possible to him who believes.