Nehemiah 10:39
For the children of Israel and the children of Levi shall bring the offering of the corn, of the new wine, and the oil, unto the chambers, where are the vessels of the sanctuary, and the priests that minister, and the porters, and the singers: and we will not forsake the house of our God.
The verse belongs to the gathering at Jerusalem where Ezra with the priests and Levites read the book of the law distinctly, gave its sense, and caused the people to understand, with careful explanation made necessary because intermarriage with other nations had corrupted the Hebrew language. It records the commitment that the children of Israel and the children of Levi would bring the offering of grain, new wine, and oil to the chambers where the vessels of the sanctuary were kept and where the ministering priests, gatekeepers, and singers were supported.
The pledge not to forsake the house of God means continuing to provide for the sanctuary and its worship. It is a covenant to support public worship and not abandon the house of God.
As part of that same covenant, in addition to the tithe, the congregation pledged a yearly stated sum for the service of the sanctuary. They also pledged to bring the firstfruits of the ground and the firstfruits of all fruit of all trees year by year to the house of the Lord. They further pledged the firstborn of sons and of cattle as written in the law, along with the firstlings of herds and flocks.