No citation is provided for the following quote, supposedly from Luther:
“They set up twelve articles which of some are so just, that they do shame to you before God and world. But almost all of them are in their favour and not drawn up to the best. […] But it is unbearable to tax and slave-drive people like this forever.”
Yes, this is from the Ermahnung zum Frieden auf die zwölf Artikel der Bauerschaft in Schwaben (Admonition to Peace, Concerning the Twelve Articles of the Peasants in Swabia), which Luther published in April 1525. The German is here and a full English translation can be found here.
As paradoxical as it may seem for the first man in the West who permanently and successfully divorced "being a Christian" from loyalty to the papacy, Luther was a stickler for authority. He even admonished Lutheran women whose husbands remained loyal to Rome that they should practice Catholic rituals and faith as well--obedience to the proper order of society was more important than getting the theology right!
So here, Luther has no problem pointing out that yes, many measures taken by princes and lords are unjust. The Bible certainly has words for the rich who exploit the poor. And it's not for no reason that leading Catholics channeled blame for the Peasants' War at Luther--many of the peasants' claims overlapped with Luther's ideas, used the idiom of Luther's ideas (appealing to "God's law"/sola scriptura as the only basis for secular legal issues of land control), and so forth. In Ermahnung zum Frieden, he talks about the core one: the right to choose the community's own preacher. This was actually a longstanding grievance of peasant and urban communities from the late Middle Ages, but it took on a whole new significance when "choosing a preacher" didn't mean wanting a good one over a bad one but wanting one who would preach a whole different theology.
BUT Luther also had that distinctive political theology of obedience to authority. The peasants were oppressed, but he did not afford them any right to fix their situation. That responsibility rested solely on the lords. So the first half of Ermahnung is an appeal to princes and lords to recognize that many of their actions are indeed abuses, and to reform because otherwise there will be violence. The second half of the text addresses the Peasants' War masterminds, excorciating them for taking up arms and vowing that God will smite them for their violence.