There are those who [generously] scatter abroad, and yet increase more; there are those who withhold more than is fitting or what is justly due, but it results only in want. (Proverbs 11:24)
The people curse him who holds back grain [when the public needs it], but a blessing [from God and man] is upon the head of him who sells it. (Proverbs 11:26)
If you want others to help you later, help others now.
If you want God to bless you later, bless others now.
If you want people to honor you later, be honorable now.
It will only come back to you IF you throw it first!