The extremely Truthful or Sidd??q is one — who does not lie in any sense and does not perform any action unless he knows that it is right. And he does not say anything unless he knows it’s true.
Undoubtedly, such a person sees nothing but the Truth and Reality. Therefore, he is one who sees the reality of things, speaks the Truth, and performs that which is the Truth.
Those who have Faith in Allah and His Messengers—it is they who are the Truthful and witnesses with their Lord; they shall have their reward and their light. But as For those who are Faithless and deny Our signs, they shall be the inmates of hell.(57: 19)