John Gill

What mean ye, that ye beat my people to pieces,.... Reduce them to the utmost poverty; so the Targum, "wherefore do ye impoverish my people?'' as they did by exacting tithes of all that they possessed; by requiring large sums for their long prayers; and by various traditions they enjoined them to observe: and grind the faces of the poor? either by smiting them on the cheek, as Christ, who became poor for our sakes, was smitten by them; or by bringing them into such low circumstances, by their exorbitant demands, that they had not sufficiency of food to eat; by which means their faces became pale, thin, and meagre: saith the Lord God of Hosts: who saw all their actions, and was able to plead his people's cause, and take vengeance on their oppressors.