"Moses prevailed. God granted his earnest petition not to blot out His people. Moses took the tables of the covenant, the law of Ten Commandments, and descended from the mount. The boisterous, drunken revelry of the children of Israel reached his ears long before he came to the camp. When he saw their idolatry, and that they had broken in a most marked manner the words of the covenant, he became overwhelmed with grief and indignation at their base idolatry. Confusion and shame on their account took possession of him, and he there threw down the tables and broke them. As they had broken their covenant with God, Moses, in breaking the tables, signified to them that so also God had broken His covenant with them. The tables whereupon was written the law of God were broken. 3T 298.1"
"And it came to pass, as soon as he came nigh unto the camp, that he saw the calf, and the dancing: and Moses’ anger waxed hot, and he cast the tables out of his hands, and brake them beneath the mount."
The EGW passage directly recounts and interprets the event described in Exodus 32:19, including the detail of Moses breaking the tablets.
"Aaron, with his amiable disposition, so very mild and pleasing, sought to conciliate Moses, as though no very great sin had been committed by the people, over which he should feel thus deeply. Moses asked in anger: “What did this people unto thee, that thou hast brought so great a sin upon them? And Aaron said, Let not the anger of my Lord wax hot: thou knowest the people, that they are set on mischief. For they said unto me, Make us gods, which shall go before us: for as for this Moses, the man that brought us up out of the land of Egypt, we wot not what is become of him. And I said unto them, Whosoever hath any gold, let them break it off. So they gave it me: then I cast it into the fire, and there came out this calf.” Aaron would have Moses think that some wonderful miracle had transformed their golden ornaments into the shape of a calf. He did not relate to Moses that he, with other workmen, had wrought out this image. 3T 298.2"
"And Moses said unto Aaron, What did this people unto thee, that thou hast brought so great a sin upon them?"
The EGW passage quotes directly from Exodus 32:21 and elaborates on the surrounding narrative.