build on sand
Use an unstable foundation, as in If you buy nothing but high-risk stocks, your portfolio will be built on sand. This metaphor appears in the New Testament, where Jesus likens those who do not heed his sayings to a foolish man who builds his house on sand, which then is washed away by rain, flood, and wind (Matthew 7:24–27). [c. 1600]
Words nearby build on sand
build, build down, build in, build into, build on, build on sand, build up, build-down, buildable, builder, builder's knot
The American Heritage® Idioms Dictionary
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