John Calvin Reformed @genevareformer

But God, on the contrary, says, Behold I will come to thee, or against thee, and will visit thee. There is, indeed, a change of number; for he says, I will visit you, for he had begun by saying, “Ye who say,” האמרים, eamrim.

Matthew Henry Presbyterian @wholebiblehenry

By the civil message which the king sent to Jeremiah it appeared that both he and the people began to have a respect for him, which it would have been Jeremiah's policy to make some advantage of for himself; but the reply which God obliges him to make is enough to crush the little respect they begin to have for him, and to exasperate them against him more than ever.

Commenting on Jeremiah 21:8-14

John Gill Reformed Baptist @doctorgill

But I will punish you according to the fruit of your doings, saith the Lord,.... The situation of their city, and the strength of its fortifications, however sufficient they might be thought to keep out an enemy from annoying them; yet it was impossible to hinder the Lord's coming among them, as he here threatens to do; and "visit" them, as the word signifies, in...