The 288th prohibition is that we are forbidden from inflicting punishment or taking money from someone on the testimony of a single witness, even if he is perfectly acceptable.

The source of this prohibition is G‑d's statement1 (exalted be He), "One witness must not testify against a person to inflict any punishment or penalty." Our Sages explained,2 "He must not testify "to inflict any punishment or penalty; but he may testify to require an oath."3

The details of this mitzvah are explained in various passages in tractates Yevamos, Kesuvos, Sotah, Gittin, Kiddushin, and a number of places in Seder Nezikin.