How to teach a toddler not to become stubborn?

By saying NO to them, you have to slowly tell them why you say NO to them. Let them know what is what and not just a NO to them. (If you are asking someone and the person keep on only say NO to you, how you feel) If like , they are playing something danger you stop them by saying NO. You have to slowly tell them why I stop you because of danger by if you do that you hurt yourself and there will be blood on you or you will cut yourself.