Charles Ellicott Commentary Isaiah 16:9

"Therefore I will weep with the weeping of Jazer for the vine of Sibmah; I will water thee with my tears, O Heshbon, and Elealeh: for upon thy summer fruits and upon thy harvest the [battle] shout is fallen." — Isaiah 16:9 (ASV)

Therefore I will bewail with the weeping of Jazer ... —The prophet, in his sympathy with the sufferings of Moab , declares that he will weep with tears as genuine as those of Jazer itself over the desolation of its vineyards.

The shouting for thy summer fruits ... —Better, as in the margin, on thy summer-fruits, and on thy harvest a shout is fallen, that is, not the song of the vintage gatherers and the reapers, but the cry of the enemy as they trample on the fields and vineyards. The force of the contrast is emphasized, as in Jeremiah 48:33 (“a cheer which is no cheer,” Cheyne), by the use of the same word (hedad) as that which in the next verse is employed for the song of those that tread the grapes. (Compare to Jeremiah 25:30.) Possibly the word for “harvest” is used generically as including the vintage.