What is the importance of truthfulness in Islam regarding personal and professional relationships, and is it permissible to lie in certain situations?

Truthfulness is the utterance of truth that conforms to reality. Islam has commanded it and forbidden lying due to its benefits and the grave harm of falsehood. Truthfulness guides to righteousness and to Paradise; it is tranquility, while lying guides to wickedness and to the Fire; it is doubt. Truthfulness encompasses being truthful with Allah through one's soul and with people in dealings. The most heinous form of lying is lying about Allah and His Messenger. Lying has been permitted in specific cases, such as reconciling disputants, in a man's conversation with his wife, and in warfare. Truthfulness in covenants and promises is considered one of the greatest forms of truthfulness.