C. F. Keil and Franz Delitzsch on Nehemiah 6:9

Neh 6:9 “For,” adds Nehemiah when writing of these things, “they all desired to make us afraid, thinking (לאמר) their hands will cease from the work, that it be not done.” The last words, “And now strengthen my hands,” are to be explained by the fact that Nehemiah hastily transports himself into the situation and feelings of those days when he prayed to God for strength. To make this request fit into the train of thought, we must supply: I however thought, or said, Strengthen, O God, my hands. חזּק is imperative. The translation, in the first pers. sing. of the imperfect, “I strengthened” (lxx, Vulg., Syr.), is only an attempt to fit into their context words not understood by the translators.

A false prophet, hired by Tobiah and Sanballat, also sought, by prophesying that the enemies of Nehemiah would kill him in the night, to cause him to flee with him into the holy place of the temple, and to protect his life from the machinations of his enemies by closing the temple doors. His purpose was, as Nehemiah subsequently learned, to seduce him into taking an illegal step, and so give occasion for speaking evil of him.