41 Jesus sat down opposite the place where the offerings were put and watched the crowd putting their money into the temple treasury. Many rich people threw in large amounts. 42 But a poor widow came and put in two very small copper coins, worth only a few cents.

43 Calling his disciples to him, Jesus said, “Truly I tell you, this poor widow has put more into the treasury than all the others. 44 They all gave out of their wealth; but she, out of her poverty, put in everything—all she had to live on.”

There's a formalism in math/information theory describing this idea called the Kelly criterion. Not a common/colloquial phrase, but it describes a similar idea of portioning bet size according to percentage of available cash based on the risk of the bet.

I really appreciate this comment! (I think that word just popped into my head given some professional experience recently rather than being sourced from the field.)