Corpus of Electronic Texts Edition
The Expulsion of the Dessi (Author: Unknown)
paragraph 3
Hence Achaill was built by the side of Tara, that is to say, a rath was dug by Cormac in which he would always sleep; for it was not lawful for a king with a blemish to sleep in Tara. Hence is said Achaill by Tara (or near Tara), on account of the care (faichill) taken of the eye of the King.