"Sidq" which is one of the common characteristics of the prophets means that they are truthful and honest people. Truthfulness and honesty are qualities sought in all people. However, these qualities are compulsory for the prophets. The words of the prophets are completely truthful. Lying (kidhb), which is the opposite of “sidq”, is unattributable for prophets. 

Prophets did not tell lies before or after prophethood. Even those who insist on denial did not accuse the prophets of lying. In this respect, our Beloved Prophet Muhammad (saw), who represented the quality of truthfulness in the best way, was called "al-sadiq al-amin", "Muhammad al-Amin" even before his prophethood and was never accused of lying by the polytheists. Abu Jahl told Prophet, "We don't call you a liar. Because we know you are amin (faithful) and trustworthy. We only deny the verses of Allah." The Messenger of Allah was so upset to hear it, and the Almighty Allah ordered as follows to console His Prophet: "O Muhammad! We know that you are saddened by what they say. And indeed, they do not call you untruthful, but it is the verses of Allah that the wrongdoers reject."(An’am, 6/33)

All of the prophets are reliable and trustworthy. The quality of "amanah" of the prophets expresses their reassuring character for people in every field. They were always sensitive to the duties and responsibilities entrusted to them and have never committed breach of trust. "Khiyanah" which is the opposite of "amanah" is a quality that is unattributable for prophets. The Almighty Allah states the following about the trustworthiness of His prophets: " It is not [attributable] to any prophet that he would act unfaithfully [in regard to war booty]." (Ali 'Imran, 3/161) Being equitable in their actions and judgments is also considered within scope of the trustworthiness of the prophets. 

The recognition of the prophets as trustworthy in the society they live in has facilitated the acceptance of the messages they brought from Allah and it also made it easier for them to be taken as an example.