build on sand

Idioms  

1. 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]

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Example Sentences

Otherwise, we are trying to build on sand or air or something equally insubstantial.

From Forbes

To use them for a foundation is to build on sand.

From Project Gutenberg

If you falter, or fail to fulfil this Golden Rule, though you should build to the heavens, you would build on sand.

From Project Gutenberg

To build on selfishness is to build on sand.

From Project Gutenberg

Those, therefore, who build arguments as to the needlessness of religion on the foundation that persons without any belief in God do exhibit all the moral virtues, build on sand.

From Project Gutenberg