"In the renewal of the covenant shortly before the birth of Isaac, God's purpose for mankind was again made plain. “All the nations of the earth shall be blessed in him,” was the assurance of the Lord concerning the child of promise. Genesis 18:18 . And later the heavenly visitant once more declared, “In thy seed shall all the nations of the earth be blessed.” Genesis 22:18 . PK 368.1"
"Seeing that Abraham shall surely become a great and mighty nation, and all the nations of the earth shall be blessed in him?"
EGW directly quotes Genesis 18:18.
"And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice."
Ellen White directly references Genesis 22:18 in this passage.
"The all-embracing terms of this covenant were familiar to Abraham's children and to his children's children. It was in order that the Israelites might be a blessing to the nations, and that God's name might be made known “throughout all the earth” ( Exodus 9:16 ), that they were delivered from Egyptian bondage. If obedient to His requirements, they were to be placed far in advance of other peoples in wisdom and understanding; but this supremacy was to be reached and maintained only in order that through them the purpose of God for “all nations of the earth” might be fulfilled. PK 368.2"
"And in very deed for this cause have I raised thee up, for to shew in thee my power; and that my name may be declared throughout all the earth."
EGW directly quotes Exodus 9:16.
"And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed."
While not a direct quote, the concept of Israel being a blessing to all nations echoes the promise in Genesis 12:3. The connection is thematic and significant to the overall argument EGW is making.