Exodus 19:11

19:11 and be ready for the third day, for on the third day the Lord will come down on Mount Sinai in the sight of all the people.

Exodus 24:16

24:16 The glory of the Lord resided on Mount Sinai, and the cloud covered it for six days. On the seventh day he called to Moses from within the cloud.

Exodus 31:18

31:18 He gave Moses two tablets of testimony when he had finished speaking with him on Mount Sinai, tablets of stone written by the finger of God.