cast one's bread upon the waters, to

To invest one’s time, money, or effort without expecting an immediate return or reward. The term comes from the Book of Ecclesiastes (11:1)—“Cast thy bread upon the waters: for thou shalt find it after many days”—urging the congregation to give generously, for one day they would indeed be rewarded. A more modern example is, “Cast your bread upon the waters and it will come back to you—buttered” (Elbert Hubbard, Book of Epigrams, 1911).