Jamieson, Fausset and Brown on Nehemiah 10:39

39. and we will not forsake the house of our God--This solemn pledge was repeated at the close of the covenant as an expression of the intense zeal by which the people at this time were animated for the glory and the worship of God. Under the pungent feelings of sorrow and repentance for their national sins, of which apostasy from the service of the true God was the chief, and under the yet fresh and painful remembrance of their protracted captivity, they vowed, and (feeling the impulse of ardent devotion as well as of gratitude for their restoration) flattered themselves they would never forget their vow, to be the Lord's.