Whoever is kind to the poor lends to the LORD,
and he will reward them for what they have done.
Those who give to the poor will lack nothing,
but those who close their eyes to them receive many curses.
There's always a tension when it comes to giving. I have a limited amount of money and if I give some of that money to feed the poor, fund missions, or support my church; then I have less money to pay my bills, feed my family, and spend on the things I want to do. That's the rub; and my greed, my logic will always try to talk me out of giving sacrificially for those reasons. Frankly, I can always make a logical argument for me needing to keep more of my money to care for my family.
But God's knows this about me, about us, and He meets us right at our place of need. And when it comes to helping poor people (a group which God shows particular concern for) He takes that excuse off the table. God tells us in the proverbs above that when we give to the poor, He charges it to His account. (Jesus says the same about poor believers in Matthew 25:31-46.) He takes it personally. He treats it as a personal loan made to Him, and He promises to pay us back.
This creates a paradox of sorts. We give but we are promised we will never lack for having given. Proverbs 11:24-25 puts it a little differently, It says "One person gives freely, yet gains even more; another withholds unduly, but comes to poverty. A generous person will prosper." So then as Matthew Henry notes, those who give to the poor are "never the poorer for having given." It could be said that giving to the poor is the surest form of investment.
Giving sacrificially is an act of trusting God that He will give enough back to me to make sure my family's needs are met. This makes giving an act of faith in God's sovereignty over my finances. He's in control of how much comes my way, if I obey Him then I can trust Him to continue to meet my needs in one way or another.
Do you trust God to pay off His loans? Do you trust Him to keep His word? Will you step out on faith and give to meet the needs of those starving all across the world? Is your faith strong enough to give sacrificially, to give 'til it hurts a little? Trust God! Give and see what He will do.