thou shalt swear. Reference to Pentateuch (Deuteronomy 10:20).
in truth, in judgment, and in righteousness. Figure of speech Hendiatris (App-6). truly, yea, justly and righteously, the three referring to the one thing, "shalt swear".
Related Commentaries of Jeremiah 4:2
Jeremiah 4:2
2 And thou shalt swear, The LORD liveth, in truth, in judgment, and in righteousness; and the nations shall bless themselves in him, and in him shall they glory.