I have no bones about that

I have no bones about that is an idiom used when you want to state a fact in a way that will not allow any doubt and nobody will be able to object to. By saying you have no bones about something, you are saying you personally do not have proof that it isnt true, therefore you are willing to concede that what this person is saying is indeed a fact; by saying it like this, they wont doubt or object your response.