On some npc priests.
To add the necessary prayers to your book, give your book to your instructor. He'll add the prayers you need at that time.
Sometimes using a ritual from a faith rod requires a specific prayer that your instructor won't give you. In this case, you need to give your prayer book to someone whose instructor does give that prayer, have them consecrate your book to their god and give your book to their instructor, then you can reconsecrate it back to your god with all of the prayers intact.
Alternatively, you can transfer prayers between prayer books dedicated to the same God by using the 'copy' syntax. Thus, you can obtain all possible prayers from any other member of your own faith who already possesses them. If you dislike the crossed-out names which normally result from the reconsecration method, you can buy a new book after collecting all the prayers and copy from the crossed-out book to the pristine new one.
- Glory be unto <deity> (prayer books come with this one)
- The Strange Travels of <deity> (for Lost Highways)
- <deity>'s coat of Many Colours (for Holy Couturequisition)
- Sands through the hourglass (for Far Sight)
- Shackles of the Spirit (for Feedback)
- Impressions of the faithful (for Divine Sentinel)
- Darkness of the soul (for Profound Darkness)
- Eyes of Io
- Piercing the veil (for Unquiet Spirit)
- Walking the path (for Raise Dead Pet)
St. Orotund's Prayer Book
In the new curiosity shop on Grunefair, there's a rotating stock which sometimes contains an Illuminated Breviary. Acts exactly the same as a prayer book but with a funkier name and description.