12 Cruel are those who do not keep your secrets; they will not spare you harm or imprisonment. 13 Be on your guard and very careful, for you are walking about with your own downfall. 15 Every creature loves its like, and every person the neighbor. 16 All living beings associate with their own kind, and people stick close to those like themselves. 17 What does a wolf have in common with a lamb? No more has a sinner with the devout. 18 What peace is there between a hyena and a dog? And what peace between the rich and the poor? 19 Wild asses in the wilderness are the prey of lions; likewise the poor are feeding grounds for the rich. 20 Humility is an abomination to the proud; likewise the poor are an abomination to the rich.
Rabba bar Mari explains each of the sources. It is written in the Torah, as it is written: “And so Esau went to Ishmael” (Genesis 28:9). It is repeated in the Prophets, as it is written: “And there were gathered vain fellows to Yiftah, and they went out with him” (Judges 11:3). And it is triplicated in the Writings, as it is written: All fowl will live with its kind, and men with those like him (Book of Ben Sira 13:17). We learned it in a mishna (Kelim 12:2): All that is attached to that which is ritually impure is ritually impure; all that is attached to that which is ritually pure is ritually pure. And we learned it in a baraita: Rabbi Eliezer says: Not for naught did the starling go to the raven but because it is its kind, as it too is a non-kosher bird.