Prophet Muhammad’s position
Prophet Muhammad’s title before his prophet hood among his tribe was (the truthful the trust worthy).
It was very common that Muhammad peace be upon him never told a lie through his life and his reputation was beyond any question.
There are many situations that support his position
There are many situations that support that, one of them is: When the prophet peace be upon him gathered all of Qurish tribe and said to them : ( If I told you that there’s a huge army behind this mountain and they want to attack you, would you believe me?) They said : ( We never heard a lie out of you).
Then he said : ( I am a warner to you before the painful punishment comes). But the Arabs disbelievers didn’t believe out of arrogance, they never thought that prophet Muhammad is a liar.
God said:”” We know that you, [O Muhammad], 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.”” Chapter 6″(33)