If the only way people will believe what you say is by having it independently verified, you have a problem.
Whether as an individual or as an organization, the reception of what you say demonstrates your credibility with your audience. If you say something, and they believe you, with few or no questions, you obviously have credibility in their eyes. However, if the only way they’ll believe you is through special pleading or the verification of a third party, you have an issue with credibility.
And typically, if people are slow to believe and trust you, there’s a reason. It’s possible that they don’t know you very well, and they don’t yet have a reason to regard you as credible. Or, if that’s not the case, perhaps it’s because of things that were done, or not done, in the past that are affecting their trust of what you say. As we all know, trust is earned, and once it’s broken, it can be take much time and effort to regain.
Delivering on your promises consistently over a period of time is the thing that builds credibility. And once you have it, people are more likely to take you at your word, whatever you say, because they have a good reason to.