Mattityahu 23:27-28

Oy to you, Sofrim and Perushim, tzevuim, for you are like kevarim (graves) having been whitewashed, which on the outside indeed appear ois vaist (ostensibly) shein (beautiful), but on the inside are full of the unclean bones of the mesim (dead ones) and every trayfnyak. Thus on the outside you indeed appear tzaddikim (righteous ones) to Bnei Adam, but on the inside you are full of tzeviut (hypocrisy) and you are lawlessly against the Torah.