"In his study of the causes leading to the Babylonish captivity, Ezra had learned that Israel's apostasy was largely traceable to their mingling with heathen nations. He had seen that if they had obeyed God's command to keep separate from the nations surrounding them, they would have been spared many sad and humiliating experiences. Now when he learned that notwithstanding the lessons of the past, men of prominence had dared transgress the laws given as a safeguard against apostasy, his heart was stirred within him. He thought of God's goodness in again giving His people a foothold in their native land, and he was overwhelmed with righteous indignation and with grief at their ingratitude. “When I heard this thing,” he says, “I rent my garment and my mantle, and plucked off the hair of my head and of my beard, and sat down astonied. PK 620.1"
"Neither shalt thou make marriages with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son."
The EGW passage explains Ezra's actions in light of the principle established in Deuteronomy 7:3, which forbids intermarriage with heathen nations.
"“Then were assembled unto me everyone that trembled at the words of God of Israel, because of the transgression of those that had been carried away; and I sat astonied until the evening sacrifice.” Verses 3, 4 . PK 620.2 At the time of the evening sacrifice Ezra rose, and, once more rending his garment and his mantle, he fell upon his knees and unburdened his soul in supplication to Heaven. Spreading out his hands unto the Lord, he exclaimed, “O my God, I am ashamed and blush to lift up my face to Thee, my God: for our iniquities are increased over our head, and our trespass is grown up unto the heavens. PK 620.3"
"Then were assembled unto me every one that trembled at the words of the God of Israel, because of the transgression of those that had been carried away; and I sat astonied until the evening sacrifice."
The EGW passage directly quotes Ezra 9:4 and provides commentary on it. This is a clear and direct allusion.
"For all those things hath mine hand made, and all those things have been, saith the Lord: but to this man will I look, even to him that is poor and of a contrite spirit, and trembleth at my word."
Both passages emphasize the importance of trembling at God's word. Ezra trembled because of the sins of the people, and Isaiah speaks of God looking favorably on those who tremble at His word. While not a direct quote, the thematic connection is strong.