Jamieson, Fausset and Brown on Hosea 3:5

5. Afterward--after the long period ("many days," Ho 3:4) has elapsed.

return--from their idols to "their God," from whom they had wandered.

David their king--Israel had forsaken the worship of Jehovah at the same time that they forsook their allegiance to David's line. Their repentance towards God is therefore to be accompanied by their return to the latter. So Judah and Israel shall be one, and under "one head," as is also foretold (Ho 1:11). That representative and antitype of David is Messiah. "David" means "the beloved." Compare as to Messiah, Mt 3:17; Ep 1:6. Messiah is called David (Is 55:3, 4; Jr 30:9; Eze 34:23, 24; 37:24, 25).

fear the Lord and his goodness--that is, tremblingly flee to the Lord, to escape from the wrath to come; and to His goodness," as manifested in Messiah, which attracts them to Him (Jr 31:12). The "fear" is not that which "hath torment" (1Jo 4:18), but reverence inspired by His goodness realized in the soul (Psa 130:4).

the latter days--those of Messiah [Kimchi].