| Gill's Exposition of the Entire Bible Take heed now that ye fail not to do this,.... To put his orders into execution, and at once, without any loss of time, oblige the Jews to desist from rebuilding the walls of their city, which he was told they were doing, though a great falsehood: why should damage grow to the hurt of the kings? of him and his successors, to be deprived of their toll, tribute, and customs, and to have insurrections, mutinies, and rebellions, in the dominions belonging to them.
Keil and Delitzsch Biblical Commentary on the Old Testament"And be warned from committing an oversight in this respect," i.e., take heed to overlook nothing in this matter (זהיר, instructed, warned). "Why should the damage become great (i.e., grow), to bring injury to kings?"
Geneva Study BibleTake heed now that ye fail not to do this: why should damage grow to the hurt of the kings?
Matthew Henry's Concise Commentary4:6-24 It is an old slander, that the prosperity of the church would be hurtful to kings and princes. Nothing can be more false, for true godliness teaches us to honour and obey our sovereign. But where the command of God requires one thing and the law of the land another, we must obey God rather than man, and patiently submit to the consequences. All who love the gospel should avoid all appearance of evil, lest they should encourage the adversaries of the church. The world is ever ready to believe any accusation against the people of God, and refuses to listen to them. The king suffered himself to be imposed upon by these frauds and falsehoods. Princes see and hear with other men's eyes and ears, and judge things as represented to them, which are often done falsely. But God's judgment is just; he sees things as they are. | 
