A fourth work, the "Kitab al-Natf" (The Book of Extracts), is known to have been written by Hayyuj, but only a fragment, unpublished as of the beginning of the 20th century, and a few quotations by later authors have survived. This was a supplement to his two grammatical works on the verb, and in it he noted the verbs omitted by him in the former treatises. In doing this he anticipated in a measure ibn Janah's "Mustalhaq" which was devoted to this very purpose. He arranged and discussed the verbal stems in question, not alphabetically, but in the order in which they occur in the Bible.