Keil & Delitzsch, on Neh 13:6

In all this, i.e., while this was taking place, I was not in Jerusalem; for in the thirty-second year of Artaxerxes I went to the king, and after the lapse of some days I entreated the king (נשׁאל like Sa1 20:6, Sa1 20:28). What he entreated is not expressly stated; but it is obvious from what follows, "and I came to Jerusalem," that it was permission to return to Judea. Even at his first journey to Jerusalem, Nehemiah only requested leave to make a temporary sojourn there, without giving up his post of royal cup-bearer; comp. Neh 2:5. Hence, after his twelve years' stay in Jerusalem, he was obliged to go to the king and remain some time at court, and then to beg for fresh leave of absence. How long he remained there cannot be determined, - ימים לקץ, after the lapse of days, denoting no definite interval; comp. Gen 4:3. The view of several expositors, that ימים means a year, is devoid of proof. The stay of Nehemiah at court must have lasted longer than a year, since so many illegal acts on the part of the community as Nehemiah on his return discovered to have taken place, could not have occurred in so short a time. Artaxerxes is here called king of Babylon, because the Persian kings had conquered the kingdom of Babylon, and by this conquest obtained dominion over the Jews. Nehemiah uses this title to express also the fact that he had travelled to Babylon.