If I mistake not, the introduction of these eminent servants of God in this place, in order to show the Church how they approached to worship the Lord, and were heard and answered, is with a view to encourage all the Lord's heritage to approach, and in the same way; for it was at the mercy-seat, meaning Christ. In him they were heard; and for his sake they were accepted. Exodus 16:10-11; Numbers 12:5.
Related Commentaries of Psalms 99:6
Psalms 99:6-7
6 Moses and Aaron among his priests, and Samuel among them that call upon his name; they called upon the LORD, and he answered them.
7 He spake unto them in the cloudy pillar: they kept his testimonies, and the ordinance that he gave them.