“Speak truthfully so that Allah may reform your deeds” (Surah al-Ahzab, 33:70)
Truthfulness is one of the most basic things for the establishment of mutual social relations. Islam has, therefore, attached much importance to truthfulness as a moral value and the Holy Qur'an has mentioned it on various occasions.
People trust a man who speaks rightly and truthfully. They hold him in esteem and accept every word of his to be correct.
On the other hand, if a man tells lies and talks foolishly and extravagantly, he loses credit in the eyes of the people and Almighty Allah is also displeased with him.
If we always talk wisely and are truthful, Allah helps us in doing good and useful things, and in leading a prosperous life. We should always remember that truthfulness is the basis of one's dignity and honour.