A man's time, when well husbanded, is like a cultivated field, of which a few acres produce more of what is useful to life, than extensive provinces, even of the richest soil, when over-run with weeds and brambles.
But all prospect of success in life, or even of tolerable subsistence, must fail, where a reasonable frugality is wanting.
 David Hume, An Enquiry Concerning the Principles of Morals (1751). copy citation

Context

“What need is there to display the praises of industry, and to extol its advantages, in the acquisition of power and riches, or in raising what we call a FORTUNE in the world? The tortoise, according to the fable, by his perseverance, gained the race of the hare, though possessed of much superior swiftness. A man's time, when well husbanded, is like a cultivated field, of which a few acres produce more of what is useful to life, than extensive provinces, even of the richest soil, when over-run with weeds and brambles. But all prospect of success in life, or even of tolerable subsistence, must fail, where a reasonable frugality is wanting. The heap, instead of increasing, diminishes daily, and leaves its possessor so much more unhappy, as, not having been able to confine his expences to a large revenue, he will still less be able to live contentedly on a small one.” source