Hosea 5:9

‘Ephraim will become a desolation in the day of rebuke,

Among the tribes of Israel have I made known what will surely be.'

The consequence of the invasion, and the certainty of those consequences, is now described. Ephraim will become a desolation (a virtual desert) on the ‘day of rebuke (chastisement, punishment)'. This was Hosea's equivalent of ‘the day of YHWH' of Amos. God was about to ‘have His day' in fulfilment of His warnings of judgment. And the certainty of it (‘what will surely be') is underlined, a certainty which YHWH has made known to ‘the tribes of Israel' (sometimes called ‘the ten tribes').