"As Moses listened to these reproaches he was greatly distressed. The sufferings of the people had been much increased. All over the land a cry of despair went up from old and young, and all united in charging upon him the disastrous change in their condition. In bitterness of soul he went before God, with the cry, “Lord, wherefore hast Thou so evil entreated this people? why is it that Thou hast sent me? For since I came to Pharaoh to speak in Thy name, he hath done evil to this people; neither hast Thou delivered Thy people at all.” The answer was, “Now shalt thou see what I will do to Pharaoh: for with a strong hand shall he let them go, and with a strong hand shall he drive them out of his land.” Again he was pointed back to the covenant which God had made with the fathers, and was assured that it would be fulfilled. PP 259.1"
"And Moses returned unto the Lord, and said, Lord, wherefore hast thou so evil entreated this people? why is it that thou hast sent me?"
The EGW passage directly quotes Exodus 5:22.
"During all the years of servitude in Egypt there had been among the Israelites some who adhered to the worship of Jehovah. These were sorely troubled as they saw their children daily witnessing the abominations of the heathen, and even bowing down to their false gods. In their distress they cried unto the Lord for deliverance from the Egyptian yoke, that they might be freed from the corrupting influence of idolatry. They did not conceal their faith, but declared to the Egyptians that the object of their worship was the Maker of heaven and earth, the only true and living God. They rehearsed the evidences of His existence and power, from creation down to the days of Jacob. The Egyptians thus had an opportunity to become acquainted with the religion of the Hebrews; but disdaining to be instructed by their slaves, they tried to seduce the worshipers of God by promises of reward, and, this failing, by threats and cruelty. PP 259.2"
"And it came to pass in process of time, that the king of Egypt died: and the children of Israel sighed by reason of the bondage, and they cried, and their cry came up unto God by reason of the bondage."
Both passages discuss the Israelites' suffering in Egypt and their cries for deliverance. EGW expands on the details of their faith and the Egyptians' response, but the core theme of suffering and crying out is present in both.
The elders of Israel endeavored to sustain the sinking faith of their brethren by repeating the promises made to their fathers, and the prophetic words of Joseph before his death, foretelling their deliverance from Egypt. Some would listen and believe. Others, looking at the circumstances that surrounded them, refused to hope. The Egyptians, being informed of what was reported among their bondmen, derided their expectations and scornfully denied the power of their God. They pointed to their situation as a nation of slaves, and tauntingly said, “If your God is just and merciful, and possesses power above that of the Egyptian gods, why does He not make you a free people?” They called attention to their own condition. They worshiped deities termed by the Israelites false gods, yet they were a rich and powerful nation. They declared that their gods had blessed them with prosperity, and had given them the Israelites as servants, and they gloried in their power to oppress and destroy the wor…
"And Moses spake so unto the children of Israel: but they hearkened not unto Moses for anguish of spirit, and for cruel bondage."
Both passages discuss the Israelites' discouragement and lack of faith due to their suffering in Egypt. The EGW passage expands on the reasons for their discouragement and the Egyptians' mockery, while Exodus 6:9 simply states their lack of faith. The connection is strong and meaningful.