I Need A Proverb?

Can you give us a context, Antonia.

Off the top of my head I can think of "house of cards", "don't build your house upon sand",
"shaky foundations"

I don't know the context, a friend of mine asked me. I called her and she told me sth like this: It is important to invest wisely your money (into a firm, when you set up a company), so that it pays off in the end.

I think the exact context is. As an old proverb says: "..."

"Don't put all your eggs in one basket"?
"a fool and his money are soon parted",
"you need money to make money",
"don't throw good money after bad"
"every mickle macks a muckle" (every little bit saved turns into a lot)
"throw your bread upon the waters" (to make an investment in something for potential gains)
"look before you leap"
" a penny saved is a penny earned"
"penny wise, pound foolish"

***"look after the pennies and the ponds will take care of themselves" ***

Are you referring to the Bible parable about the man who built his house on stone and the man who built his house on sand?

No, I just need a proverb to fit into a text about financing.
Thank you

"Don't buy a pig in a poke" - i.e. check everything out very carefully before you invest.

How about "the chain is only as strong as its weakest link"?