"We cannot get out. We cannot get out. They have taken the bridge and Second Hall. Frár and Lóni and Náli fell there bravely while the rest retr [...] Mazarbul. We still ho[...]g ... but hope u[...]n[...]Óin’s party went five days ago but today only four returned. The pool is up to the wall at West-gate. The Watcher in the Water took Óin--we cannot get out. The end comes soon. We hear drums, drums in the deep. They are coming"
Gandalf discovered the Book of Mazarbul when the Fellowship entered the Mines of Moria; he gave the book to Gimli, who passed it on to Dáin.
Mazarbul means "record" in the Dwarf-language of Khuzdul.