John Calvin Commentary Psalms 94:4

"They prate, they speak arrogantly: All the workers of iniquity boast themselves." — Psalms 94:4 (ASV)

They pour forth, they speak hard things. He shows in still clearer terms how their fierceness in persecution was such that they did not scruple to glory in their guilt. The Hebrew verb נבע, nabang, means more than to speak. Literally, it signifies to rush or boil forth, and comes to denote figuratively the uttering of reckless or rash words.

We see how wicked men are instigated by pride and vainglory to demean and disgrace themselves so far as to boast vaingloriously of their power, breathing out threats of bloodshed, violence, and monstrous cruelty. It is to such ebullitions that the Psalmist refers, when men who are lost to all sense of shame and modesty boast of the wickedness which they can perpetrate at will.

This is what he means by their speaking hard things, uttering discourse that is under no restraint of fear or prudential consideration, but which launches into the most unbridled license. As the Lord’s people formerly had to endure the heavy trial of seeing the Church subjected to this wild tyranny and misrule, we should not consider it strange to see the Church still suffering under miserable misgovernment or positive oppression, but should pray for help from God, who, though He connives at wickedness for a time, eventually comes to the deliverance of His children.