enchiridion \en-kahy-RID-ee-uhn, noun:

A handbook; manual.

For you offer us the postulation that we can, in the shadow, or rather the radiance, of your own enchiridion, go and do likewise.
— Marcel Proust, Swann’s Way

Sarah and Isaac were romping noisily about and under the beds; Rachel was at the table, knitting a scarf for Solomon; grandmother pored over a bulky enchiridion for pious women, written in jargon.
— Israel Zangwill, Children of the Ghetto

Enchiridion stems from the Greek root cheir meaning “hand”. The prefix en- means “within”, so the noun means “in the hand”. The suffix -idion denotes a diminutive form of another word.