מדרש על סנהדרין 200:3

The Alphabet is apparently the work of a late author who pored over the book of Ben Sira and selected from it several sayings and several other things that were said in his name in the Aramaic language which was then the common language among the masses, and organized them alphabetically as a mnemonic aid. And after him came a second author who made a second alphabet, in the Holy Tongue, because he found some Talmudic and Midrashic content, and appended it to them in order to complete the alphabet. And after him came a third author, and appended to these a commentary