The verse means: "Show hospitality, even though the corresponding return of hospitality to you may seem improbable; nevertheless, be hospitable in faith." Compare Luke 14:13-14; Hebrews 13:2. Some interpreters (not unreasonably) understand by "bread" the seed from the produce of which bread is made. Seed cast upon the fertile soil flooded by the early rains would be returned to the sower in autumn with large increase.

Cast thy bread upon the waters - An allusion to the sowing of rice; which was sown upon muddy ground, or ground covered with water, and trodden in by the feet of cattle: it thus took root, and grew, and was found after many days in a plentiful harvest. Give alms to the poor, and it will be as seed sown in good ground. God will cause thee afterwards to receive it with abundant increase. The Targum understands it of giving bread to poor sailors. The Vulgate and my old Bible have the same idea. Send thi brede upon men passing waters.

Cast thy bread upon the (a) waters: for thou shalt find it after many days.
(a) That is, be liberal to the poor, and though it seems to be as a thing ventured on the sea, yet it will bring you profit.

Cast thy bread upon the waters,.... As the wise man had often suggested that nothing was better for a man than to enjoy the good of his labour himself, he here advises to let others, the poor, have a share with him; and as he had directed in the preceding chapter how men should behave towards their superiors, he here instructs them what notice they should take of their inferiors; and as he had cautioned against luxury and intemperance, he here guards against tenacity and covetousness, and exhorts to beneficence and liberality: that which is to be given is "bread", which is put for all the necessaries of life, food and raiment; or money that answers all things, what may be a supply of wants, a support of persons in distress; what is useful, profitable, and beneficial; not stones or scorpions, or what will be useless or harmful: and it must be "thy" bread, a man's own; not independent of God who gives it him; but not another's, what he owes another, or has fraudulently obtained; but what he has got by his own labour, or he is through divine Providence in lawful possession of; hence alms in the Hebrew language is called "righteousness": and it must be such bread as is convenient and fit for a man himself, such as he himself and his family eat of, and this he must cast, it must be a man's own act, and a voluntary one; his bread must not be taken and forced from him; it must be given freely, and in such a manner as not to be expected again; and bountifully and plentifully, as a man casts seed into the earth; but here it is said to be "upon the waters"; bread is to be given to such as are in distress and affliction, that have waters of a full cup wrung out unto them, whose faces are watered with tears, and foul with weeping, from whom nothing is to be expected again, who can make no returns; so that what is given thorn seems to be cast away and lost, like what is thrown into a river, or into the midst of the sea; and even it is to be given to such who prove ungrateful and unthankful, and on whom no mark or impression of the kindness is made and left, no more than upon water; yea, it is to be given to strangers never seen before nor after, like gliding water; so the Vulgate Latin version renders it, "passing waters": or else to such who may be compared to well watered ground, or "moist ground", as Mr. Broughton renders it; where the seed cast will grow up again, and bring forth fruit, and redound to the advantage of the sower, as what is given to the poor does; they are a good soil to sow upon, especially Christ's poor, who are partakers of his living water, grace; see Isaiah 32:20; though it may be the multitude of persons to whom alms is to be given are here intended, which are sometimes signified by waters, Revelation 17:15; as Ecclesiastes 11:2 seems to explain it. The Targum is,
"reach out the bread of thy sustenance to the poor that go in ships upon the thee of the water;''
and some think the speech is borrowed from navigation, and is an allusion to merchants who send their goods beyond sea, and have a large return for them;
for thou shalt find it after many days; not the identical bread itself, but the fruit and reward of such beneficence; which they shall have unexpectedly, or after long waiting, as the husbandman for his seed; it suggests that such persons should live long, as liberal persons oftentimes do, and increase in their worldly substance; and if they should not live to reap the advantage of their liberality, yet their posterity will, as the seed of Jonathan did for the kindness he showed to David: or, however, if they find it not again in temporal things, yet in spirituals; and shall be recompensed in the resurrection of the just, and to all eternity. So the Targum,
"for after the time of many days, then thou shall find the reward of it in this world (so it is in the king's Bible), and in the world to come;''
see Luke 12:12. Jarchi instances in Jethro. Noldius (p) renders it "within many days", even before many days are at an end; for seed sown by waters in hot climates soon sprung up, and produced fruit; see Daniel 11:20.
(p) Ebr. Concord. Partic. p. 155. No. 704.

Solomon presses the rich to do good to others. Give freely, though it may seem thrown away and lost. Give to many. Excuse not thyself with the good thou hast done, from the good thou hast further to do. It is not lost, but well laid out. We have reason to expect evil, for we are born to trouble; it is wisdom to do good in the day of prosperity. Riches cannot profit us, if we do not benefit others. Every man must labour to be a blessing to that place where the providence of God casts him. Wherever we are, we may find good work to do, if we have but hearts to do it. If we magnify every little difficulty, start objections, and fancy hardships, we shall never go on, much less go through with our work. Winds and clouds of tribulation are, in God's hands, designed to try us. God's work shall agree with his word, whether we see it or not. And we may well trust God to provide for us, without our anxious, disquieting cares. Be not weary in well-doing, for in due season, in God's time, you shall reap, Galatians 6:9.

(Ecclesiastes 11:1-10)
Ecclesiastes 11:2 shows that charity is here inculcated.
bread--bread corn. As in the Lord's prayer, all things needful for the body and soul. Solomon reverts to the sentiment (Ecclesiastes 9:10).
waters--image from the custom of sowing seed by casting it from boats into the overflowing waters of the Nile, or in any marshy ground. When the waters receded, the grain in the alluvial soil sprang up (Isaiah 32:20). "Waters" express multitudes, so Ecclesiastes 11:2; Revelation 17:15; also the seemingly hopeless character of the recipients of the charity; but it shall prove at last to have been not thrown away (Isaiah 49:4).

"Let thy bread go forth over the watery mirror: for in the course of many days shalt thou find it." Most interpreters, chiefly the Talm., Midrash, and Targ.,
(Note: The Midrash tells the following story: Rabbi Akiba sees a ship wrecked which carried in it one learned in the law. He finds him again actively engaged in Cappadocia. What whale, he asked him, has vomited thee out upon dry land? How hast thou merited this? The scribe learned in the law thereupon related that when he went on board the ship, he gave a loaf of bread to a poor man, who thanked him for it, saying: As thou hast saved my life, may thy life be saved. Thereupon Akiba thought of the proverb in Ecclesiastes 11:1. Similarly the Targ.: Extend to the poor the bread for thy support; they sail in ships over the water.)
regard this as an exhortation to charity, which although practised without expectation of reward, does not yet remain unrewarded at last. An Aram. proverb of Ben Sira's (vid., Buxtorf's Florilegium, p. 171) proceeds on this interpretation: "Scatter thy bread on the water and on the dry land; in the end of the days thou findest it again." Knobel quotes a similar Arab. proverb from Diez' Denkwrdigkeiten von Asien (Souvenirs of Asia), II 106: "Do good; cast thy bread into the water: thou shalt be repaid some day." See also the proverb in Goethe's Westst. Divan, compared by Herzfeld. Voltaire, in his Prcis de l'Ecclsiaste en vers, also adopts this rendering:
Repandez vos bien faits avec magnificence,
Mme aux moins vertueux ne les refusez pas.
Ne vous informez pas de leur reconnaissance -
Il est grand, il est beau de faire des ingrats.
That instead of "into the water (the sea)" of these or similar proverbs, Koheleth uses here the expression, "on the face of (על־פּני) the waters," makes no difference: Eastern bread has for the most part the form of cakes, and is thin (especially such as is prepared hastily for guests, 'ughoth or matstsoth, Genesis 18:6; Genesis 19:3); so that when thrown into the water, it remains on the surface (like a chip of wood, Hosea 10:7), and is carried away by the stream. But שׁלּח, with this reference of the proverb to beneficence, is strange; instead of it, the word השׁלך was rather to be expected; the lxx renders by ἀπόστειλον; the Syr., shadar; Jerome, mitte; Venet. πέμπε; thus by none is the pure idea of casting forth connected with שׁלּח. And the reason given does not harmonize with this reference: "for in the course of many days (berov yamin, cf. mērov yamim, Isaiah 24:22) wilt thou find it" (not "find it again," which would be expressed by תּשׁוּב תּם). This indefinite designation of time, which yet definitely points to the remote future, does not thus indicate that the subject is the recompense of noble self-renunciation which is sooner or later rewarded, and often immediately, but exactly accords with the idea of commerce carried on with foreign countries, which expects to attain its object only after a long period of waiting. In the proper sense, they send their bread over the surface of the water who, as Psalm 107:33 expresses, "do business in great waters." It is a figure taken from the corn trade of a seaport, an illustration of the thought: seek thy support in the way of bold, confident adventure.
(Note: The Greek phrase σπείρειν πόντον, "to sow the sea" = to undertake a fruitless work, is of an altogether different character; cf. Amos 6:12.)
Bread in לח is the designation of the means of making a living or gain, and bread in תּמצאנּוּ the designation of the gain (cf. Ecclesiastes 9:11). Hitzig's explanation: Throw thy bread into the water = venture thy hope, is forced; and of the same character are all the attempts to understand the word of agricultural pursuits; e.g., by van der Palm: sementem fac muxta aquas (or: in loca irrigua); Grtz even translates: "Throw thy corn on the surface of the water," and understands this, with the fancy of a Martial, of begetting children. Mendelssohn is right in remarking that the exhortation shows itself to be that of Koheleth-Solomon, whose ships traded to Tarshish and Ophir. Only the reference to self-sacrificing beneficence stands on a level with it as worthy of consideration. With Ginsburg, we may in this way say that a proverb as to our dealings with those who are above us, is followed by a proverb regarding those who are below us; with those others a proverb regarding judicious courageous venturing, ranks itself with a proverb regarding a rashness which is to be discountenanced; and the following proverb does not say: Give a portion, distribute of that which is thine, to seven and also to eight: for it is well done that thou gainest for thee friends with the unrighteous mammon for a time when thou thyself mayest unexpectedly be in want; but it is a prudent rule which is here placed by the side of counsel to bold adventure:

The waters - Freely and liberally bestow it upon the waters; upon those poor creatures, on whom it may seem to be as utterly lost, as the seed which a man casts into the sea or river. Find it - It shall certainly be restored to thee, either by God or men. This is added to prevent an objection, and to quicken us to the duty enjoyned. After - The return may be slow, but it is sure, and will be so much the more plentiful.