Matthew Poole and continuators on Proverbs 20:21

21 An inheritance may be gotten hastily at the beginning , but the end thereof shall not be blessed .

An Estate somtimes is got suddenly in the very beginning of a Man's labours for it, in which case it may be presumed that some undirect and unrighteous courses were used, for the getting of it, because Riches are very seldom given by God, or gotten by men, without mens diligence. But this, as well as many other Proverbs, are to be understood of the common course, although it admit of some exceptions. For somtimes Merchants or others get great Estates speedily by one happy Voyage, or by some other prosperous event. This Translation follows the Hebrew Marginal reading, but according to the Textual reading, it may be thus rendered and understood, An Inheritance gotten in the beginning (to wit, of a mans indeavours) is abominable, to wit, unto God, being supposed to be unjustly gotten, as was now said.

At last it shall be cursed and wither by God's just judgment.

Marginal references: Ch. 28. 20.