And they said unto Moses, &c.— They, that is, the heads of the tribes, the elders of the people. See ch. Exodus 19:7 and Deuteronomy 5:23 where this event is related more at large.
Related Commentaries of Exodus 20:19
Exodus 20:19
19 And they said unto Moses, Speak thou with us, and we will hear: but let not God speak with us, lest we die.