Joel 2:27
And ye shall know that I am in the midst of Israel, and that I am the LORD your God, and none else: and my people shall never be ashamed. And ye shall know that I am in the midst of Israel, and that I am the LORD your God, and none else: and my people shall never be ashamed.
The promise is grace held out after apostasy and bitter retribution to those who repent, by which the broken relationship between God and Israel is restored. After restoring what was lost and providing abundantly, He takes away His people's reproach. Then they know that He is present in their midst and that He alone is their God, and as His people they will never be put to shame. They are satisfied and praise Him for His wondrous care.
The same chapter gives authority for lay young men to go forth preaching the warning that the hour of God's judgment has come. The Spirit comes upon them with such power that they cannot hold back from preaching. That outpouring is the answer when governors and priests and police demand by what authority they preach. Even when men try to stop them by arrest and scourging and imprisonment, the work goes forward under that power.