וְאֶ֨ת־בָּר֔וּךְ שָׁאֲל֖וּ לֵאמֹ֑ר הַגֶּד־נָ֣א לָ֔נוּ אֵ֗יךְ כָּתַ֛בְתָּ אֶת־כָּל־הַדְּבָרִ֥ים הָאֵ֖לֶּה מִפִּֽיו׃
And they asked Baruch, saying: ‘Tell us now: How didst thou write all these words at his mouth?’
Read midrashic interpretation of Jeremiah 36:17: and classical rabbinic exegesis.