Talmud zu Jeschijahu 46:1

And a stranger [ger] shalt thou not wrong, neither shalt thou oppress him:¹Ex. 22, 20. you shall not wrong him in speech or oppress him in money dealings. Do not say to him,²What follows is according to MS.K. For Bel, etc., cf. Isa. 46, 1, Bel boweth down (קרס), Nebo stoopeth, alluding to Babylonian deities. ‘Yesterday you were worshipping Bel, Ḳores and Nebo, and till now pig’s flesh was between your teeth, and now you stand up and speak with me!’ And whence [do I learn] [not] to wrong him? He can retort, For ye were strangers in the land of Egypt?³Ex. loc. cit. [The more correct version is found in Mekilta ad loc.: ‘If you wrong him he is able to wrong you? Therefore there is a saying, For ye were strangers, etc.’ Hence R. Nathan used to say: Do not taunt your neighbour with the blemish which you yourself have.⁴[Cf. B.M. 59b (Sonc. ed.,p. 356).]