In The Name of Allaah, The Most Merciful, The Bestower of Mercy

Shaikhul Islaam Ibn Taymiyyah [rahimahullaah] said:

Lying against an individual is absolutely forbidden- whether the man [i.e. the one lied against] is a Muslim or a disbeliever, righteous or a wicked sinner-; but fabricating lies against a believer is more severe.

[Majmoo Al-Fataawaa 28/223]