Genesis 28:20-22
20 Then Jacob made a vow, saying, “If God will be with me and will watch over me on this journey I am taking and will give me food to eat and clothes to wear 21 so that I return safely to my father’s household, then the Lord[a] will be my God 22 and[b] this stone that I have set up as a pillar will be God’s house, and of all that you give me I will give you a tenth.”
2 Corinthians 9:6-7
6 Remember this: Whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously. 7 Each of you should give what you have decided in your heart to give, not reluctantly or under compulsion, for God loves a cheerful giver.