Exode 32:20

And he took the calf which they had made, and burned it in fire, and bruised it into powder, and cast (it) upon the face of the water of the stream, and made the sons of Israel drink; and whoever had given thereto any trinket of gold, the sign of it came forth upon his nostrils.

AND HE STREWED IT UPON THE WATER, AND MADE THE CHILDREN OF ISRAEL DRINK IT. After grinding the golden calf to a fine powder, he scattered it on the surface of the stream which came down from the mountain, and made the people drink of those waters. It is possible that gold burnt in fire does not melt, but instead when placed therein is charred and can be ground to powder, as Rabbi Abraham ibn Ezra mentioned. This powder was light upon the face of the waters, and therefore it floated, and he made them drink of it. Or it may be that he scattered it upon the stream in small quantities, and then drew the water and made them drink it before the gold powder sank in the stream. Or perhaps it was a miraculous event. Thus he wanted to disgrace their deeds by grinding their god to powder and bringing it into their bellies to issue as excrement, something like it is said, Thou shalt put them [i.e., the graven images] far away as one unclean; thou shalt say unto it: ‘get thee hence.’ In the opinion of our Rabbis he also intended to put them to the test in the same way that faithless wives were tried, [so that those guilty of having worshipped the golden calf] would have their bellies swell and their thighs fall away., Verse 27. This is the truth.

ויזר, same as ויפזר, “he scattered.” The construction from the root פזר is parallel to vayiken, from the root kanah, (compare Genesis 33,19) Compare also the root זרה which would be vayizer as here. We find the word in this sense in Numbers 17,2 ואת האש זרה הלאה, “and throw the fire (flame) away.”

וישק את בני ישראל, he examined their truthfulness by making them drink this mixture, just as a Sotah suspected of infidelity has to drink water [mixed with ground dust].

וישק את בני ישראל, “he made the Children of Israel drink;” on this verse Rashi observes that basically we are subject to death for certain sins by one of three types of death, a) as in the case where a woman has been suspected of infidelity by her husband, when there are no eyewitnesses to the supposed infidelity. In such cases death is brought about by Divine interference, the woman who had lied by protesting her innocence having to drink the “bitter” water, as a result of which she will die a painful death. [Compare Numbers 5,27) b) a capital offence was committed by a person who had been duly warned of the consequence of his deed by two legally qualified witnesses. The death penalty will be carried out by the guilty party being killed by the sword. Compare Deuteronomy 13,17, as explained by the Talmud, tractate Sanhedrin, folio 111. c) there are witnesses to the sin having been committed, but the sinner had not been warned immediately prior to committing the sin by qualified witnesses. In that case he will die by a plague at the instigation of G–d. If Rashi were correct in comparing the death of the people worshipping the golden calf were executed by the sword as the people in Deuteronomy 13,17, why was their property not destroyed as is the case there? We would have to answer that they were punished as if they had been gentiles, where destruction of the sinner’s property is not decreed. (Compare Talmud, tractate Sanhedrin folio 56)