Exodus 19:9

9 And the Lord said to Moses, Lo! I come to thee in a pillar of a cloud, that the people may hear me speaking to thee, and may believe thee for ever: and Moses reported the words of the people to the Lord.

Exodus 19:9 In-Context

7 And Moses came and called the elders of the people, and he set before them all these words, which God appointed them.
8 And all the people answered with one accord, and said, All things that God has spoken, we will do and hearken to: and Moses reported these words to God.
9 And the Lord said to Moses, Lo! I come to thee in a pillar of a cloud, that the people may hear me speaking to thee, and may believe thee for ever: and Moses reported the words of the people to the Lord.
10 And the Lord said to Moses, Go down and solemnly charge the people, and sanctify them to-day and to-morrow, and let them wash their garments.
11 And let them be ready against the third day, for on the third day the Lord will descend upon mount Sina before all the people.

The Brenton translation of the Septuagint is in the public domain.