Charles Ellicott Commentary Exodus 19:8

"And all the people answered together, and said, All that Jehovah hath spoken we will do. And Moses reported the words of the people unto Jehovah." — Exodus 19:8 (ASV)

All the people answered together. —There was no hesitation, no diversity of opinion, no self-distrust. In view of the great privileges offered to them, all were willing, or rather, eager, to promise for themselves that “they would obey God’s voice indeed, and keep his covenant.” In the glow and warmth of their feelings the difficulty of perfect obedience did not occur to them.

Moses returned the words —that is, “took them back,” “reported them.”