'Tenths' in the Bible

Will a man keep back from God what is right? But you have kept back what is mine. But you say, What have we kept back from you? Tenths and offerings.

Let your tenths come into the store-house so that there may be food in my house, and put me to the test by doing so, says the Lord of armies, and see if I do not make the windows of heaven open and send down such a blessing on you that there is no room for it.