For I say unto you, That unto every one which hath shall be given; and from him that hath not, even that he hath shall be taken away from him.
λέγω ὑμῖν ὅτι παντὶ τῷ ἔχοντι δοθήσεται, ἀπὸ δὲ τοῦ μὴ ἔχοντος καὶ ὃ ἔχει ἀρθήσεται.
Parallels at Matthew 13:12, 25:29; Mark 4:25; Luke 8:18; Gospel of Thomas 41. How this might happen in practice we see from Juvenal 3.203-220 (tr. G.G. Ramsay). Two dwellings have burned down, that of the poor man Codrus, and that of the rich man Asturicus:
Codrus possessed a bed too small for the dwarf Procula, a sideboard adorned by six pipkins, with a small drinking cup, and a recumbent Chiron below, and an old chest containing Greek books whose divine lays were being gnawed by unlettered mice. Poor Codrus had nothing, it is true: but he lost that nothing, which was his all; and the last straw in his heap of misery is this, that though he is destitute and begging for a bite, no one will help him with a meal, no one offer him lodging or shelter.
But if the grand house of Asturicus be destroyed, the matrons go dishevelled, your great men put on mourning, the praetor adjourns his court: then indeed do we deplore the calamities of the city, and bewail its fires! Before the house has ceased to burn, up comes one with a gift of marble or of building materials, another offers nude and glistening statues, a third some notable work of Euphranor or Polyclitus, or bronzes that had been the glory of old Asian shrines. Others will offer books and bookcases, or a bust of Minerva, or a hundredweight of silver-plate.
lectus erat Cordo Procula minor, urceoli sex
ornamentum abaci, nec non et parvulus infra
cantharus et recubans sub eodem marmore Chiron,
iamque vetus Graecos servabat cista libellos
et divina opici rodebant carmina mures.
nil habuit Cordus, quis enim negat? et tamen illud
perdidit infelix totum nihil. ultimus autem
aerumnae cumulus, quod nudum et frusta rogantem
nemo cibo, nemo hospitio tectoque iuvabit.
si magna Asturici cecidit domus, horrida mater,
pullati proceres, differt vadimonia praetor.
tum gemimus casus urbis, tunc odimus ignem.
ardet adhuc, et iam accurrit qui marmora donet,
conferat inpensas; hic nuda et candida signa,
hic aliquid praeclarum Euphranoris et Polycliti,
haec Asianorum vetera ornamenta deorum,
hic libros dabit et forulos mediamque Minervam,
hic modium argenti.
See also Martial 5.81 (tr. Walter C.A. Ker):
You will always be poor, if you are poor, Aemilianus. Wealth is given to-day to none save the rich.
semper pauper eris, si pauper es, Aemiliane.
dantur opes nulli nunc nisi divitibus.