Malachi 3:13

Among the people of the Jews at this time, though they all enjoyed the same privileges and advantages, there were men of very different characters (as ever were, and ever will be, in the world and in the church), like Jeremiah's figs, some very good and others very bad, some that plainly appeared to be the children of God and others that as plainly discovered themselves to be the children of the wicked one. There are tares and wheat in the same field, chaff and corn in the same floor; and here we have an account of both. I. Here is the angry notice God takes of the impudent blasphemous talk of the sinners in Zion and his just resentments of it. Probably there was a club of them that were in league against religion, that set up for wits, and set their wits on work to run it down and ridicule it, and herein strengthened one another's hands. Here is, 1. An indictment found against them, for treasonable words spoken against the King of kings: Your words have been stout against me, saith the Lord. They spoke against God, in reflection upon him, in contradiction to him, as their fathers in the wilderness (Psa 78:19); yea, they spoke against God. What he said, and what he designed, they opposed, as if they had been retained of counsel against him and his cause. Their words against God were stout; they came from their pride, and haughtiness, and contempt of God.

— Matthew Henry's Concise Commentary (public domain)

He notices the complaint of the Jews that it is of no profit to serve Jehovah, for that the ungodly proud are happy; and declares He will soon bring the day when it shall be known that He puts an everlasting distinction between the godly and the ungodly. words . . . stout--Hebrew, "hard"; so "the hard speeches which ungodly sinners have spoken against Him" (Jde 1:15) [HENDERSON]. have we spoken--The Hebrew expresses at once their assiduity and habit of speaking against God [VATABLUS]. The niphal form of the verb implies that these things were said, not directly to God, but of God, to one another (Eze 33:20) [MOORE].

— Jamieson-Fausset-Brown Commentary (public domain)