Is it permissible for me to bear false witness in court regarding something I did not see, for the benefit of a trustworthy person, knowing that my testimony will not harm anyone?

Testimony is legal proof that reveals the truth. It is the act of informing about what one knows using specific wording. Its matter is grave and serious. Allah the Almighty says: "And do not conceal testimony, for whoever conceals it - his heart is sinful." It is not permissible for anyone to testify to something they did not witness, because that falls under false testimony, which is one of the greatest sins. It is permissible for you to testify before the judge that you have never experienced a lie from so-and-so and that you trust his truthfulness.