Albert Barnes Commentary Nehemiah 9:38

"And yet for all this we make a sure covenant, and write it; and our princes, our Levites, [and] our priests, seal unto it." — Nehemiah 9:38 (ASV)

Seal to it - The exact force of the phrase used is doubtful; but its general sense must be that the classes named took part in the sealing. It was usual in the East to authenticate covenants by appending the seals of those who were parties to them .