Jerome

Surely the nations are like a drop in a bucket; they are regarded as dust on the scales; he weighs the islands as though they were fine dust. LXX: Behold, all the nations are as a drop in a bucket and are accounted as the dust on the scales. All peoples who did not know their Creator or the whole human race in comparison to God are like a drop from a bucket and like a speck of dust on a scale that tilts lightly to one side. …

Commentary on Isaiah ↗

Thomas Aquinas

Third, he shows its excellence, that it exceeds all the multitude of nations: behold the Gentiles are as a drop, a little spot, of a bucket, falling from a bucket, which is a vessel of water fit for the thirsty, which is accounted as nothing; the smallest grain, which is between the arms of a balance and is easily inclined to either: seeing we have heard scarce a little drop of his word, who shall be able to behold the thunder of his greatness? (Job 26:14).

Commentary on Isaiah ↗

Bonaventure

And just as all things compared to the divine power can do virtually nothing, so all things compared to the divine essence are virtually the least. Whence in respect to the divine being this entire world is as something minimal. And this is what is said in Wisdom eleven: For as a grain in the balance, so is the whole world before you, and as a drop of morning dew that falls upon the earth: and in Isaiah forty: Behold, the nations are as a drop from a bucket and are accounted as a grain in the balance: and afterward: All nations are …

Quaestiones Disputatae, De Mysterio Trinitatis, Question 4 ↗