Then said I, Ah, Lord God!.... The word hha, "Ah", or "Ahah", is used in distress and grief, as Kimchi observes; and is expressive of mourning and complaint, as Jarchi notes; and shows that the prophet was troubled and uneasy at his call, and would gladly have been excused on the following account:behold, I cannot speak; or, "I know not how to speak" ; properly and pertinently, politely and eloquently, especially before great personages, kings and princes, and the citizens of Jerusalem, being brought up in a rustic manner in the country.
A like excuse Moses made, Ex 4:10. The Targum is, "I know not to prophesy: for I am a child"; meaning either in knowledge and understanding, or in years; not a mere child, but a "junior", as the Septuagint version renders the word; or a "young man", as the Arabic version; so Samuel and Zechariah were young men, when they first ministered in their office, 1Sa 3:1.
Abarbinel supposes that Jeremiah was now twelve or fifteen years of age; but it should seem rather that he was more, perhaps twenty years of age; since he seems to have prophesied to the men of Anathoth before he was sent to Jerusalem, Jer 11:21.
rbd ytedy al "uescio loqui", V. L.