John Gill Commentary Proverbs 3:28

"Say not unto thy neighbor, Go, and come again, And to-morrow I will give; When thou hast it by thee." — Proverbs 3:28 (ASV)

Say not unto your neighbor
Either to whom you are indebted, and who comes for the payment of a just debt; or to any poor and indigent person that applies for alms:

go, and come again, and tomorrow I will give ;
go home, and come tomorrow, and I will pay you what I owe you; or do not trouble me now, come another time, and perhaps I may relieve your wants: this should not be said, because a man cannot be sure of tomorrow that he shall ever see it; nor may it be in the power of his hands, should he live unto the morrow, to do as he promises; his substance may be taken from him; and besides, in the mean time, the poor object may perish for want of relief;

when you have it by you ;
money to pay your debts with, or to give alms to the poor; and therefore should give readily and at once, and not make any excuses and delays; "bis dat, qui cito dat". Some make this to be part of the covetous man's words, saying, "and there is with you"; or you have enough, you have no need to ask of me; you have what you ask; you are not in want; you are richer than I; but the other sense is best.

The Septuagint and Arabic versions add, ``for you know not what the day following may bring forth;'' or may happen on it.