Neither their silver nor their gold will be able to save them on the day of the Lord’s wrath

 Zephaniah 1:1-18

During the reign of Josiah son of Amon king of Judah.

Be silent before the Sovereign Lord, for the day of the Lord is near. The Lord has prepared a sacrifice; he has consecrated those he has invited.

On that day I will punish all who avoid stepping on the threshold, who fill the temple of their gods with violence and deceit.

At that time I will search Jerusalem with lamps and punish those who are complacent,  who are like wine left on its dregs, who think, ‘The Lord will do nothing, either good or bad.’

Neither their silver nor their gold will be able to save them on the day of the Lord’s wrath.” In the fire of his jealousy the whole earth will be consumed, for he will make a sudden end of all who live on the earth.

Why?

The Lord declared the "Great day of the Lord" would come up in Jerusalem, Judah. People in Jerusalem did not sense that the end of their lives was coming.

At that time is the day God defined or decided. We don't know when or how? It is in the hands of the Lord. Usually, we might think it won't happen, "The Lord will do nothing, either good or bad." like people of Judah though.

How?

The word of the Lord will come truth, the Lord is full of mercy and gives us the time to repent. At that time is not chance to repent for our sins.