Midrasch zu Mischlej 18:13

(Ib. b) It is written in the book of Ben Sira: I have weighed everything on the scale and did not find a thing to be lighter than bran; however, a groom who resides in the house of his father-in-law is lighter than bran; and still lighter than he is a guest who brings with him an uninvited companion; and still lighter is the one who answers before he has heard thoroughly the question, as it is said (Prov. 18, 13) When one returneth an answer before he understandeth (the question) it is folly unto him and a shame.