The demon Foras appears in the grimoires The Discoverie of Witchcraft, The Book of Spirits, The Book of the Office of Spirits, The Book of Oberon, Pseudomonarchia Daemonum, The Lesser Key of Solomon, and Dictionnaire Infernal
From The Lesser Key of Solomon, Crowley/Mathers edition:
Foras
The Thirty-first Spirit is Foras. He is a Mighty President, and appeareth in the Form of a Strong Man in Human Shape. He teacheth the Arts of Logic and Ethics in all there parts. If desired he maketh men invisible, 2 and to live long, and to be eloquent. He can discover Treasures and recover things Lost. He ruleth over 29 Legions of Spirits, and his Seal is this, which wear thou, etc.