What is the ruling on forging a certificate of experience to obtain a better job, knowing that the person possesses the required experience and has not harmed anyone?

A person who signs in the name of his manager has erred because it is a lie and forgery, and he must repent. As for his new job with this certificate: if he obtained a genuine certificate from the first company, then there is no blame on him, along with his repentance. But if he did not obtain it, then he should not continue in the new job because it is based on deception.