Jeremiah 1:6 - Joseph Benson’s Commentary on the Old and New Testaments

Then said I, Ah, Lord God, &c. He modestly excuses himself from a consideration of the weight of the work, and the tenderness of his age, as in the next expression. Behold, I cannot speak; for I am a child We cannot infer from this, that Jeremiah was within the years of what is properly called childhood. For he might call himself a child by way of extenuating his abilities; as Solomon calls himself a little child, 1 Kings 1:7, although at that time he was married, and must have been at least twenty years of age. And the word child, or youth, is elsewhere used of those who were arrived at the first years of manhood.