13. Gird yourselves—namely, with sackcloth; as in Isa 32:11, the ellipsis is supplied (compare Jer 4:8).
lament, ye priests—as it is your duty to set the example to others; also as the guilt was greater, and a greater scandal was occasioned, by your sin to the cause of God.
come—the Septuagint, "enter" the house of God (compare Joe 1:14).
lie all night in sackcloth—so Ahab (1Ki 21:27).
ministers of my God—(1Co 9:13). Joel claims authority for his doctrine; it is in God's name and by His mission I speak to you.