The Prophet (s) said: "Truth is the adornment of speech."
Imam as-Sadiq (a) said: "Do not be deceived by their very much offering of prayers and observance of fasting. In fact, prayers and fasting have become habits that they feel desolate if they omit them. You should test them by their truthfulness and fulfillment of trusts."
"The deeds of the truthful are growing."
This means that the deeds of the truthful are ongoing and their rewards are, too, growing. Thus, God accepts only the deeds of the pious ones. Truth, then, is one of the most significant characteristics of piety.
Achievements of Truth
The publicity of mutual understanding between individuals is a social necessity. If they commit themselves to so, they will have the ability to shoulder the burdens of life and enjoy a peaceful coexistence. It goes without saying that tongue is the instrument of mutual understanding and the translator of the various concepts that rove in people's minds. It therefore plays a serious role in the existence of communities and the harmony of individuals' feelings and ideas. The happiness or distress of any society depends upon verbal truthfulness or falsehood. If tongue is truthful in interpreting the emotions, it will fulfill the mission of communication. If it, on the other hand, is characterized by mistranslation and misexpression, it will be the guide to evil and the means of social destruction. Hence, truth, whose effects and reflections play the greatest role in the individuals' lives, is a social necessity.
Parties of transactions, for instance, can save themselves and times from the fatigue of bargain if they adhere to truthfulness. If all people observe truthfulness, they will gain its innumerable benefits and advantages. If untruth, on the other hand, becomes a common phenomenon in a society, the moral principals will be