God hears our vows, the promises we make to Him in prayer. God gives us rewards, possessions, prosperity, land, and blessings. We pray this way, because we honor, are loyal to, and have reverential fear towards God.
In a believer's life making vows or promises to God is optional: you don't have to, but also natural: you want to, because as you discover God's goodness, you naturally want to make promises and vows to Him.
God is the prototypical, the first and foremost generous person. Giving is God's nature. God gives a heritage to those who honor Him.
A heritage is something that is handed down, inherited, or reserved for us. We individually have rewards, we collectively take part in the reward, and we are given to one another as a reward.
I believe that the heritage is "the whole package", meaning and abundant life in and with God and people. The main gift, possession, blessing, or reward that we receive is God himself. We can and do say, "Lord, You are my portion in this life".
It is not about getting things, but about getting God and God gives each one of us things. This message is portable to the poorest and richest cultures, because God gives each one a place and a space, in Him, no matter where they are. This message could have great meaning to someone in prison, for example.
We who are believers at this time, get to take part in the blessing that God has offered and given in every generation. Walking with God, making promises to Him, and honoring God results in a richly rewarding life at any time and in any place.
God has an inheritance for each of His children. You might say, "when will I receive it?", and the answer is that you are already receiving it. Look around and see it, hear it, know it.
We might ask if there is a formula, that if we make vows or promises, that we will get possessions or inheritances from God. God is not like our earthly parents or grandparents, as He gives His children their inheritances. God is the, "before you call, I will answer", God; and God gives gifts to all his children, in an unmerited fashion.
God does not give to us because we make vows or promises, but we make vows and promises because of God's generosity. We possess our inheritances because we are paying attention to God. Our rewards, special possessions, lands, monies, benefits, and unclaimed promotions are awaiting us, as we journey with and into God.