Then there's the saying, only a part of which is common in the U.S.:
"Cast your bread upon the waters . . .,"
which is from the Bible in the Old Testament book of Ecclesiastes, chapter 11, verse 1.
Taken by itself, it means your investment will bring you a return only if you release it and not keep it to yourself. In other words, throw your investment into the sea; in faith, release it.
The NET version of the Bible, however, translates the entire verse as follows:
"Send your grain overseas, for after many days you will get a return."
This complete saying makes more sense to me, in that it gives us a picture of the buyer of a large quantity of wheat (from which we make bread) who loads it on a ship and exports it overseas. There is risk in doing this, because the ship could be lost at sea, or the wheat could be ruined if the ship is flooded, or the ship's captain could abscond with the wheat, sell it, and keep the money himself.
However, if things go as planned, the risk is rewarded when the wheat is sold at a good price, and the proceeds come back to the shipper (a farmer, for example). Just as the soldier in your proverb sleeps and forgets about the work he accomplished, so too does the shipper of wheat have to relax and forget about the wheat for awhile. After a time, he will receive a return on his investment.
In Christian circles, Ecclesiastes 11:1 is often linked to the New Testament book of The Gospel of Luke, chapter 6, verse 38. In Jesus' words:
"'Give, and it will be given to you. They will pour into your lap a good measure--pressed down, shaken together, and running over. For by your standard of measure it will be measured to you in return.'"
In other words, if you give generously of your hard-earned money to people in need, sooner or later you will be rewarded generously in various ways. Not only that, but your return will be heaped up, pressed down, shaken together, and running over!
Picture two different ways of measuring brown sugar. The first way is simply to put your measuring cup into the sack of sugar and pull it out. The second, and generous, way is to scoop up the sugar, pack it down, shake the container and add more sugar, and then heap even more sugar on top so that the loose sugar spills out of the cup.
A similar thing happens when you release the fruit of your labors (your money) generously. You may not get a return on your investment right away, but when you do, the return will be a generous one. Generous people attract generosity. In other words, you are better off being generous than being stingy and cheap!