From the statements of his eminence Grand Ayatollah Mousavi Ardebili:
"Truthfulness is one of the fundamental and firm principles which has innate root and it is extremely important in Islam ... in Holy Qur’an, Allah repeatedly praised Himself, prophets and believers for truthfulness:
"Allah and his messenger have spoken in truth ", " the messengers have spoken the truth", " among the believers there are men who have been true to their covenant with Allah...", " then, when the matter is decided, if they were true to Allah it would be better for them ", " this is the day the truthful shall benefit by their truthfulness".
Also the Holy Qur'an named some of the prophets as "trustful" and praised them for this character ...
It might be speculated that the purpose of truthfulness is only in speech and not telling the truth ... but it is a much broader concept that applies only to human speech. Truthfulness means that human should not be bad understanding in his thought, action, speech, communication with himself and others and he should not be hypocrite, deceitful, cunning and crafty ...
Some people deem that truthfulness is a good thing, but not in politics. They think that politics is based on deception, fraud, lie, and tricky. So say this: If a person wants to be trustful, he should avoid politics and political activities.
The theory of lack of compatibility between politics and truthfulness is the result of misunderstanding of politics and truthfulness. Politics means managing the affairs and not deception and deceit. Managing the affairs is also based on the wisdom and justice and discipline ...
Politics which is not consistent with the truthfulness, is the politics of Mu`awiyah. Such politics will never have a good end. Relying on lies in the politics is a kind of misery and humiliation. "
Along with the Revolution, page 576-578, Friday Prayers Sermon of his eminence Grand Ayatollah Mousavi Ardebili, Friday, August 17, 1990, Tehran University