"Had Elisha asked Elijah what was expected of him,—what would be his work,—he would have been answered: God knows; He will make it known to you. If you wait upon the Lord, He will answer your every question. You may come with me if you have evidence that God has called you. Know for yourself that God stands back of me, and that it is His voice you hear. If you can count everything but dross that you may win the favor of God, come. PK 220.2"
"Lead me in thy truth, and teach me: for thou art the God of my salvation; on thee do I wait all the day."
Both passages emphasize waiting on God for guidance and instruction. The EGW passage speaks of waiting on the Lord to answer questions, while the Psalm speaks of being led and taught by God. The connection is thematic and relevant.