"Closing our Restaurants on the Sabbath The question has been asked: “Should our restaurants be opened on the Sabbath?” My answer is: No, no! The observance of the Sabbath is our witness to God, the mark, or sign, between Him and us that we are His people. Never is this mark to be obliterated. 7T 121"
"Speak thou also unto the children of Israel, saying, Verily my sabbaths ye shall keep: for it is a sign between me and you throughout your generations; that ye may know that I am the Lord that doth sanctify you."
EGW explicitly refers to the Sabbath as 'the mark, or sign, between Him and us' which is a direct allusion to Exodus 31:13, where the Sabbath is described as a sign between God and the Israelites.
"Were the workers in our restaurants to provide meals on the Sabbath the same as they do through the week for the mass of people who would come, where would be their day of rest? What opportunity would they have to recruit their physical and spiritual strength? 7T 121.2"
"But the seventh day is the sabbath of the Lord thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:"
The EGW passage directly applies the principle of Sabbath rest from Exodus 20:10 to the specific context of restaurant workers.