Prophet Muhammad pbuh was known as a truthful and trustworthy person long before Islam. He was known throughout Makkah as “Al-Sadiq Al-Amin“: the Truthful, Trustworthy one, a title he retained even by those who disbelieved in him after he declared his prophethood. Even Prophet Muhammad’s pbuh enemies did not accuse him of lying after he proclaimed his prophethood. Even opponents of Islam Abu Jahl used to deny the truth, i.e. this Quran but he considered Prophet Muhammed pbuh truthful and trustworthy.
Once makkan faced an issue that which tribe will lay the black stone in the holy kabbah they had decided that the one who entered the holy kabbah first will fulfill the duty. Next morning Prophet Muhammad pbuh entered the holy kabbah first, everyone was happy to see him. They were happy to see that truth full and honest person will lay the black stone in the holy kabbah.
When Qaiser of Rome asked Abu sufyan, their head: “before his claim to prophet hood did you ever heard Muhammad telling a lie? Abu sufyan replied “no”.
Abu Bakr, the best friend and loyal supporter of Prophet Mohammad pbuh. They asked him if he believed Prophet Muhammad travelled overnight to Jerusalem, and back to Mecca. Without hesitation Abu Bakr replied, “If the messenger of God said so, then it is true”. This is Abu Bar r.a statement.
Muhammad, The Last Prophet pbuh made his way to Mount Safa, the most well-known elevation in the whole of Makkah, to announce Islam to its people at a time when 360 idols were placed around the Kaaba. He felt no fear or shame. Stood on a high place, and exclaimed, ‘Ya Sabaha-hu’. His voice resounded on the mountain and attracted the attention of the people. Large crowds from various tribes hurried toward him to hear what he was going to say. Muhammad, The Last Prophet pbuh turned to them and said, ‘O people! Will you believe me if I say there is an army marching behind this mountain which is about to attack you?’
They all answered, ‘Of course we would, we have not heard a lie from you throughout your life’.
In the last year of his life, when he was delivering the Farewell Pilgrimage sermon at Mount Arafat, he reiterated the commandments of God once more. At the end of each sentence, he told the people: “In the near future, they will ask you about me.”
He then would ask them if he had conveyed the message to them, to which they responded, each time with great enthusiasm: “Yes, you have conveyed it!” He then would call upon God to witness their words (Abu Dawud).
Surely this is a reason why he was chosen by God to be a prophet, so that he would devote himself totally to delivering the message truthfully.
Undoubtedly, no one can be more truthful and honest than the Prophet Muhammad (pbuh). He proved by his life example that truthfulness and honesty of Prophet Muhammad (pbuh) is beyond comparison and He was the most honest and truthful person of his time. Everyone was impressed by truthfulness and honesty of Prophet Muhammad (pbuh).
Prophet Muhammad (PBUH) is an epitome of character and virtue, its just a slight shadow of His Character.