Charles Ellicott Commentary Jeremiah 48:31

"Therefore will I wail for Moab; yea, I will cry out for all Moab: for the men of Kir-heres shall they mourn." — Jeremiah 48:31 (ASV)

Therefore will I howl for Moab. —The changes of person are remarkable. The “I” that speaks is neither Jehovah nor the prophet, but the unnamed mourner, who in the next clause appears in the third person (she shall mourn, the English “mine heart” having no equivalent in the Hebrew) as the representative of those who mourn for Moab. In Jeremiah 48:33, I have caused wine to fail appears as the utterance of Jehovah. In Isaiah 16:7, of which the whole passage is a free reproduction, Moab is named as the mourner. Possibly, however, Jeremiah in his sympathy may speak here in his own person.

For the men of Kir-heres. —The name appears in Isaiah 16:7 as Kirhareseth, and is probably identical with Kir of Moab of Isaiah 15:1. The place was obviously an important stronghold. The Targum on Isaiah and Jeremiah renders it by Crac, and this has led to its being identified with the modern Kerak, occupying a strong position on one of the Moabite mountains to the south-east of the Dead Sea. The name, which signifies “City of the Sun,” may indicate its connection with that form of nature-worship.