"Chapter 26—From the Red Sea to Sinai This chapter is based on Exodus 15:22-27 ; 16 to 18 . From the Red Sea the hosts of Israel again set forth on their journey, under the guidance of the pillar of cloud. The scene around them was most dreary—bare, desolate-looking mountains, barren plains, and the sea stretching far away, its shores strewn with the bodies of their enemies; yet they were full of joy in the consciousness of freedom, and every thought of discontent was hushed. PP 291"
"So Moses brought Israel from the Red sea, and they went out into the wilderness of Shur; and they went three days in the wilderness, and found no water. And when they came to Marah, they could not drink of the waters of Marah, for they were bitter: therefore the name of it was called Marah. And the people murmured against Moses, saying, What shall we drink? And he cried unto the Lord; and the Lord shewed him a tree, which when he had cast into the waters, the waters were made sweet: there he made for them a statute and an ordinance, and there he proved them, And said, If thou wilt diligently hearken to the voice of the Lord thy God, and wilt do that which is right in his sight, and wilt give ear to his commandments, and keep all his statutes, I will put none of these diseases upon thee, which I have brought upon the Egyptians: for I am the Lord that healeth thee. And they came to Elim, where were twelve wells of water, and threescore and ten palm trees: and they encamped there by the waters."
Ellen White directly references Exodus 15:22-27 in this passage.
"But for three days, as they journeyed, they could find no water. The supply which they had taken with them was exhausted. There was nothing to quench their burning thirst as they dragged wearily over the sun-burnt plains. Moses, who was familiar with this region, knew what the others did not, that at Marah, the nearest station where springs were to be found, the water was unfit for use. With intense anxiety he watched the guiding cloud. With a sinking heart he heard the glad shout. “Water! water!” echoed along the line. Men, women, and children in joyous haste crowded to the fountain, when, lo, a cry of anguish burst forth from the host—the water was bitter. PP 291.2"
"So Moses brought Israel from the Red sea, and they went out into the wilderness of Shur; and they went three days in the wilderness, and found no water."
The EGW passage directly references and expands upon the event described in Exodus 15:22, where the Israelites journeyed for three days without water.
"In their horror and despair they reproached Moses for having led them in such a way, not remembering that the divine presence in that mysterious cloud had been leading him as well as them. In his grief at their distress Moses did what they had forgotten to do; he cried earnestly to God for help. “And the Lord showed him a tree, which when he had cast into the waters, the waters were made sweet.” Here the promise was given to Israel through Moses, “If thou wilt diligently hearken to the voice of the Lord thy God, and wilt do that which is right in His sight, and wilt give ear to His commandments, and keep all His statutes, I will put none of these diseases upon thee, which I have brought upon the Egyptians: for I am the Lord that healeth thee.” PP 291.3"
"And he cried unto the Lord; and the Lord shewed him a tree, which when he had cast into the waters, the waters were made sweet: there he made for them a statute and an ordinance, and there he proved them,"
The EGW passage directly quotes and elaborates on Exodus 15:25, making the connection explicit.