"You have fallen into the sad error which is so prevalent in this degenerate age, especially with women. You are too fond of the other sex. You love their society; your attention to them is flattering, and you encourage, or permit, a familiarity which does not always accord with the exhortation of the apostle, to “abstain from all appearance of evil.” 2T 248.1"
"Abstain from all appearance of evil."
EGW directly quotes 1 Thessalonians 5:22 in the context of avoiding even the appearance of impropriety.
You have written many letters, which has greatly taxed you. These letters have dwelt somewhat upon the subjects of our faith and hope; but mixed with this have been close inquiries and guesses in regard to whether this one or that one was about to marry, and suggestions relative to marriage. You seem to know considerable about anticipated marriages, and write and talk upon these things. This only causes dearth to your soul. “Out of the abundance of the heart the mouth speaketh.” You have done great injustice to yourself in permitting your mind and conversation to dwell upon love and marriage. You have not been happy, because you have been seeking after happiness. This is not profitable business. When you seek earnestly to do your duty, and arouse yourself to minister unto others, then you will find rest of spirit. Your mind dwells upon yourself. It needs to be drawn away from yourself by seeking to lighten the cares of others; and in making them happy, you will find happiness and cheer…
"O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh."
EGW directly quotes Matthew 12:34, making it an explicit allusion. The context in EGW is different, applying the principle to gossip and speculation about marriage, but the direct quote confirms the connection.