"During these days that Christ spent with His disciples, they gained a new experience. As they heard their beloved Master explaining the Scriptures in the light of all that had happened, their faith in Him was fully established. They reached the place where they could say, “I know whom I have believed.” 2 Timothy 1:12 . They began to realize the nature and extent of their work, to see that they were to proclaim to the world the truths entrusted to them. The events of Christ's life, His death and resurrection, the prophecies pointing to these events, the mysteries of the plan of salvation, the power of Jesus for the remission of sins—to all these things they had been witnesses, and they were to make them known to the world. They were to proclaim the gospel of peace and salvation through repentance and the power of the Saviour. AA 27.1"
"For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day."
Ellen White directly references 2 Timothy 1:12 in this passage.
"Before ascending to heaven, Christ gave His disciples their commission. He told them that they were to be the executors of the will in which He bequeathed to the world the treasures of eternal life. You have been witnesses of My life of sacrifice in behalf of the world, He said to them. You have seen My labors for Israel. And although My people would not come to Me that they might have life, although priests and rulers have done unto Me as they listed, although they have rejected Me, they shall have still another opportunity of accepting the Son of God. You have seen that all who come to Me confessing their sins, I freely receive. Him that cometh to Me I will in no wise cast out. To you, My disciples, I commit this message of mercy. It is to be given to both Jews and Gentiles—to Israel, first, and then to all nations, tongues, and peoples. All who believe are to be gathered into one church. AA 27.2"
"But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judea, and in Samaria, and unto the uttermost part of the earth."
Both passages deal with the commission given to the disciples to be witnesses. EGW expands on the commission, but the core idea of being witnesses is present in both.
"Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:"
The EGW passage expands on the Great Commission given in Matthew 28:19, emphasizing the universality of the gospel message and Christ's acceptance of all who come to Him.