John Gill Commentary Isaiah 16:11

"Wherefore my heart soundeth like a harp for Moab, and mine inward parts for Kir-heres." — Isaiah 16:11 (ASV)

Wherefore my bowels shall sound like a harp for Moab
Making a noise as the harp does, and a mournful one as that, when used at funerals. It makes this noise when it is stricken or played on with the hand, as these were, through the afflictive and punitive hand of God. When stricken, it causes a quavering of the strings, to which the inward trembling of the bowels is compared, and is very expressive of the prophet's sympathy, or those he personates; for, when one string of the harp is touched, the rest sound. For these words, as Kimchi says, are spoken in the language of the Moabites; those that survived lamenting the desolate state of their country, which must be very great and affecting. To show that it was so is the design of the prophet's expressing himself after this manner; for if it was painful to him, it must be much more so to them; so the Targum, ``wherefore the bowels of the Moabites shall sound as a harp;'' of the sounding of the bowels, see (Isaiah 63:15) (Jeremiah 4:9) :

and mine inward parts for Kirharesh :
the same with Kirhareseth, (Isaiah 16:7) which being a principal city, the destruction of it was greatly laid to heart. The Targum is, ``and their heart shall grieve for the men of the city of their strength;'' it being a strong city, in which they placed their confidence; but being destroyed, and the inhabitants of it, it was very affecting, to which agrees (Jeremiah 48:31) .