Ecclesiastes Rabbah 12:12

¹“More than that, my son, be careful: Making many books has no end, and much prattle is exertion of the flesh” (Ecclesiastes 12:12). “More than that [ mehema ], my son, be careful” – [of] confusion [ mehuma ], as anyone who introduces more than [these] twenty-four books into his house introduces confusion into his house, such as the book of ben Sira and the book of ben Tigla. “And much prattle is exertion of the flesh” – as they were given for prattle and were not given for exertion.