Thus can you preach against that self same vice Which you indulge and that is avarice Ch 28 99 100 who says this?

The lines you referenced are from "The Canterbury Tales," specifically from "The Pardoner's Tale," written by Geoffrey Chaucer. In this context, the Pardoner, who is a character known for his hypocrisy, is critiqued for preaching against avarice while simultaneously indulging in it himself. This highlights the theme of moral corruption and the contradictions in human behavior, particularly among those who claim to uphold moral values.