"“Even when exceedingly brain-weary, your mother seems to find great comfort in the promises of the Word, and often catches up a quotation and completes it when we begin quoting some familiar scripture.... I do not find her discouraged ... over the general outlook throughout the harvest field when her brethren are laboring. She seems to have strong faith in God's power to overrule, and to bring to pass His eternal purpose through the efforts of those whom He has called to act a part in His great work. She rises above petty criticism, above even the past failures of those who have been reproved, and expresses the conviction, born, apparently, of an innate faith in the church of the living God, that her brethren will remain faithful to the cause they have espoused, and that the Lord will continue with them to the end, and grant them complete victory over every device of the enemy. LS 436.4"
"I can do all things through Christ which strengtheneth me."
The EGW passage describes faith in God's power to overrule and bring about His purpose, which aligns with the general theme of Philippians 4:13 about finding strength in Christ to accomplish things. However, it's not a direct allusion or principle, but rather a thematic overlap.