The Punished Deeds
From Halopedia, the Halo wiki
The Punished Deeds[1] is presumed to have been a Covenant book or knowledge source where the Covenant store data. It could be similar to diary entries.
The number of volumes is unknown, but it has at least three volumes as in Halo Wars, the player can see entries into "The Punished Deeds, Vol. III"[1] in the Timeline and Events section from the title screen, after unlocking data and events.
Entries
The Punished Deeds notes that Ripa 'Moramee "has no fear of death". The Arbiter, before entering any Relic, sends in a group of Grunts to check for danger. If there was danger, he would make the Grunts detonate their methane tanks.[1]
It also notes that the Prophet of Regret used manipulation and blackmail against the High Prophet of Restraint to gain his position as a High Prophet.[1]