"Christ's Method Ministers and teachers should give special attention to the cultivation of the voice. They should learn to speak, not in a nervous, hurried manner, but with a slow, distinct, clear utterance, preserving the music of the voice. CT 239"
"So likewise ye, except ye utter by the tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air."
Both passages emphasize the importance of clear and understandable speech. The EGW quote focuses on the manner of speaking (slow, distinct, clear), while 1 Corinthians 14:9 highlights the need for easily understood words. They share a common principle.