“If God will be with me and will keep me on this journey that I take, and will give me food to eat and clothing to wear, and if [He grants that] I return to my father’s house in safety, then the Lord will be my God. This stone which I have set up as a pillar (monument, memorial) will be God’s house [a sacred place to me], and of everything that You give me I will give the tenth to You [as an offering to signify my gratitude and dependence on You].” – Genesis 28:20-22
The God of the Old Testament is utterly holy and thus transcendent, inaccessible, mysterious, and inscrutable ( Psalm 99:3-9 ). But if this alone were true about God, why worship such a terrible and awesome deity? Happily, this same God is also the “Holy One among you” ( Hosea 11:9 ), a God who at once dwells “in a high and holy place, but also with him who is contrite and lowly in spirit” ( Isa 57:15 ). God merits worship because in his eminent presence he is able to answer those who call upon him and forgive their wrongdoings ( Psalm 99:8 ). It was this intimate presence of a holy God that prompted heartfelt praise and worship ( Psalm 99:3 ) and the keen desire for holy living among the people of Israel (Lev 19:2 ).
This is not the condition on which Jacob will accept God in a mercenary spirit. “This stone shall be God’s house,” a monument of the presence of God among his people, and a symbol of the indwelling of his Spirit in their hearts. As it comes in here it signalizes the grateful and loving welcome and entertainment which God receives from his saints. The honored guest is treated as one of the family. Ten is the whole: a tenth is a share of the whole. The Lord of all receives one share as an acknowledgment of his sovereign right to all. Here it is represented as the full share given to the king who condescends to dwell with his subjects. Thus, Jacob opens his heart, his home, and his treasure to God. These are the simple elements of a theocracy, a national establishment of the true religion. The spirit of power, and of love, and of a sound mind, has begun to reign in Jacob. As the Father is prominently manifested in regenerate Abraham, and the Son in Isaac, so also the Spirit in Jacob. – Barnes Notes
The question that Jesus drives us to ask again and again is not, “How much should I give?” but rather, “How much dare I keep?” One of the differences between the Old Testament and New Testament is the Great Commission. By and large the Old Testament people of God were not a missionary people. But the New Testament church is fundamentally a missionary people. The spiritual hope and the physical and emotional sustenance that Jesus brought to earth is extended by his church to the world. The task he gave us is so immense and requires such a stupendous investment of commitment and money that the thought of settling the issue of what we give by a fixed percentage (like a tenth) is simply out of the question. In a world where 10,000 people a day starve to death and many more than that are perishing in unbelief the question is not, “What percentage must I give?” but, “How much dare I spend on myself?”