Friedrich Nietzsche (a German Philosopher) once said
"I'm not upset that you lied to me, I'm upset that from now on I can't believe you."
Trust takes years and years to build but one action is enough to destroy decades of work.
Always remember trust once broken is never fully healed. The day you broke someone's trust, that person will have doubts about you until the day you die.
For a person with integrity, Reputation is the raison d'etre. One lie is enough to obliterate your entire reputation.
So, always be very careful about your actions because it takes 20 years to build a reputation and 5 minutes to destroy it.
Be a person of morals, values and ethics and you will always sleep like a baby.