"Another who came out to welcome the victorious patriarch was Melchizedek, king of Salem, who brought forth bread and wine for the refreshment of his army. As “priest of the most high God,” he pronounced a blessing upon Abraham, and gave thanks to the Lord, who had wrought so great a deliverance by His servant. And Abraham “gave him tithes of all.” PP 136.1"
"And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God."
EGW directly references Melchizedek bringing bread and wine and being the priest of the most high God, mirroring Genesis 14:18.
"And blessed be the most high God, which hath delivered thine enemies into thy hand. And he gave him tithes of all."
The EGW passage directly quotes and references Genesis 14:20 regarding the blessing and tithes given to Melchizedek.