John Wesley on Amos 9:1

The altar - Of burnt - offering before the temple at Jerusalem, this altar and temple Israel had forsaken, and set up others against it; and here God in his jealousy appears prepared to take vengeance. Possibly it may intimate his future departure from Judah too. There Ezekiel, Eze 9:2, saw the slaughter - men stand. The door - The door of the gate that led into the priests court. And cut them - Wound deep, the people who were visionally represented as standing in the court of the temple.