Which languages ​​do the oldest grammar books have

The oldest surviving German book was a Latin-German dictionary called "Abrogans". This word is the first entry in the book that begins with the words: abrogans . .  dheomodi ("humble").

The template for the book was a Latin dictionary of synonyms that was created in Italy to explain rarer Latin words in the Bible using more common, also Latin expressions. The monks added Old High German equivalents both for the Latin keyword and for its Latin synonymous.

Since there were often no German words for its subtleties, poor paraphrase had to be used, and often had to be created first.

The name of the book (Abrogans) thus follows the same scheme as the name of our alphabet, which also contains the first two (original) terms (alpha, beta = alphabet).

The Bavarian original of the abrogan was probably around 760 AD. originated in the Freising monastery and no longer exists. There are 3 Alemannic copies from the 8th and 9th centuries that are preserved today in St. Gallen, Karlsruhe and Paris. The complete manuscript from St. Gallen is published here.

The first traces of the written German language are even a bit older than the Abrogans. They can be found in Latin manuscripts in which monks had written German words in the margin or between the lines as translation aids. About 2/3 of the Old High German vocabulary has been handed down to us through such "glosses".