Charles Ellicott Commentary Nehemiah 6:17-19

"Moreover in those days the nobles of Judah sent many letters unto Tobiah, and [the letters] of Tobiah came unto them. For there were many in Judah sworn unto him, because he was the son-in-law of Shecaniah the son of Arah; and his son Jehohanan had taken the daughter of Meshullam the son of Berechiah to wife. Also they spake of his good deeds before me, and reported my words to him. [And] Tobiah sent letters to put me in fear." — Nehemiah 6:17-19 (ASV)

A supplementary account is here introduced, explaining the intrigues within Jerusalem to which reference has been made.