"Sabbathbreaking received the same punishment, being equally an expression of contempt for the authority of God. PP 409.1"
"Ye shall keep the sabbath therefore; for it is holy unto you: every one that defileth it shall surely be put to death: for whosoever doeth any work therein, that soul shall be cut off from among his people."
EGW's statement that Sabbath breaking received the same punishment as blasphemy is a direct reflection of the principle outlined in Exodus 31:14, which prescribes the death penalty for Sabbath desecration.
"In our day there are many who reject the creation Sabbath as a Jewish institution and urge that if it is to be kept, the penalty of death must be inflicted for its violation; but we see that blasphemy received the same punishment as did Sabbathbreaking. Shall we therefore conclude that the third commandment also is to be set aside as applicable only to the Jews? Yet the argument drawn from the death penalty applies to the third, the fifth, and indeed to nearly all the ten precepts, equally with the fourth. Though God may not now punish the transgression of His law with temporal penalties, yet His word declares that the wages of sin is death; and in the final execution of the judgment it will be found that death is the portion of those who violate His sacred precepts. PP 409.2"
"And the Lord said unto Moses, The man shall be surely put to death: all the congregation shall stone him with stones without the camp."
Both passages discuss the death penalty associated with violating God's law, specifically referencing Numbers 15:35 regarding Sabbath-breaking. EGW uses this as an example to argue against dismissing the Sabbath.
"During the entire forty years in the wilderness, the people were every week reminded of the sacred obligation of the Sabbath, by the miracle of the manna. Yet even this did not lead them to obedience. Though they did not venture upon so open and bold transgression as had received such signal punishment, yet there was great laxness in the observance of the fourth commandment. God declares through His prophet, “My Sabbaths they greatly polluted.” Ezekiel 20:13-24 . And this is enumerated among the reasons for the exclusion of the first generation from the Promised Land. Yet their children did not learn the lesson. Such was their neglect of the Sabbath during the forty years’ wandering, that though God did not prevent them from entering Canaan, He declared that they should be scattered among the heathen after the settlement in the Land of Promise. PP 409.3"
"But the house of Israel rebelled against me in the wilderness: they walked not in my statutes, and they despised my judgments, which if a man do, he shall even live in them; and my sabbaths they greatly polluted: then I said, I would pour out my fury upon them in the wilderness, to consume them. But I wrought for my name’s sake, that it should not be polluted before the heathen, in whose sight I brought them out. Yet also I lifted up my hand unto them in the wilderness, that I would not bring them into the land which I had given them, flowing with milk and honey, which is the glory of all lands; Because they despised my judgments, and walked not in my statutes, but polluted my sabbaths: for their heart went after their idols. Nevertheless mine eye spared them from destroying them, neither did I make an end of them in the wilderness. But I said unto their children in the wilderness, Walk ye not in the statutes of your fathers, neither observe their judgments, nor defile yourselves with their idols: I am the Lord your God; walk in my statutes, and keep my judgments, and do them; And hallow my sabbaths; and they shall be a sign between me and you, that ye may know that I am the Lord your God. Notwithstanding the children rebelled against me: they walked not in my statutes, neither kept my judgments to do them, which if a man do, he shall even live in them; they polluted my sabbaths: then I said, I would pour out my fury upon them, to accomplish my anger against them in the wilderness. Nevertheless I withdrew mine hand, and wrought for my name’s sake, that it should not be polluted in the sight of the heathen, in whose sight I brought them forth. I lifted up mine hand unto them also in the wilderness, that I would scatter them among the heathen, and disperse them through the countries; Because they had not executed my judgments, but had despised my statutes, and had polluted my sabbaths, and their eyes were after their fathers’ idols."
Ellen White directly references Ezekiel 20:13-24 in this passage.