A Drop in the Bucket
A very small proportion of the whole.
From Isaiah 40:15:
“Behold, the nations are as a drop of a bucket, and are counted as the small dust of the balance: behold, he taketh up the isles as a very little thing.”
Drop – in its original sense of distillation, as in drop of water.
Bucket – This is the only usage of the word ‘bucket’, and it mean ‘a pail or jar for drawing water’.
Dust of the balance; of equals “on” , balance meaning scale.
Therefore Dust on the balance (scale) means “not enough to matter”, like the grain dust on the scales at the market.