Within a year - What has been said before was figurative. Here the prophet speaks without a metaphor, and fixes the time when this should be accomplished. It is not usual for the prophets to designate the exact “time” of the fulfillment of their prophecies in this manner.
According to the years of an hireling - Exactly; observing the precise time specified Job 7:1. See the phrase explained on Isaiah 16:14.
All the glory - The beauty, pride, strength, wealth, etc.
Of Kedar - Kedar was a son of Ishmael Genesis 25:15. He was the father of the Kedareneans or “Cedrai,” mentioned by Pithy (“Nat. Hist.” v. 11). They dwelt in the neighborhood of the Nabatheans, in Arabia Deserta. These people lived in tents, and were a wandering tribe, and it is not possible to fix the precise place of their habitation. They resided, it is supposed, in the south part of Arabia Deserts, and the north part of Arabia Petrea. The name ‘Kedar’ seems to be used sometimes to denote Arabia in general, or Arabia Deserts particularly (see Psalms 120:5; Song of Solomon 1:5; Isaiah 42:11; Isaiah 60:7; Jeremiah 2:10; Jeremiah 49:28; Ezekiel 26:21).
Shall fail - Shall be consumed, destroyed (כלה kâlâh).