Midrasch zu Schoftim 11:3

Raba said again unto Rabba bar Mari: "Wherefrom the following people's saying: 'Although the wine belongs to the owner, thanks is nevertheless due to the waiter?'" He answered: "From (Num. 27, 19) And thou shalt lay thy hand upon him; and also (Deut. 34, 9) And Joshua the son of Nun was full of the spirit of wisdom; for Moses had laid his hands upon him," etc. (The whole credit is given to Moses). Raba said again to Rabba bar Mari: "Wherefrom the following people's saying: 'The bad palm will travel to meet a barren can (like meets like)?'" He answered: "This is written in the Pentateuch, repeated in the Prophets, mentioned a third time in the Hagiographa, also learned in a Mishnah and taught in a Baraitha: Pentateuch, the following passage (Gen. 38, 9) And Esau went unto Ishmael; Prophets (Jud. 11, 3) And then gathered themsleves to Yiphthach idle men, and they went out with him; Hagiographa (Ben Sira, 13) Every fowl associates with its kind and man with his equal; Mishnah, "All that is attached to an unclean article is unclean and all that is attached to a clean article is clean." Baraitha: R. Eliezer said: "Not in vain did the gladiator go to the raven, because it is of its kind."