Exodus 24:4

24:4 and Moses wrote down all the words of the Lord. Early in the morning he built an altar at the foot of the mountain and arranged twelve standing stones – according to the twelve tribes of Israel.

Exodus 25:12

25:12 You are to cast four gold rings for it and put them on its four feet, with two rings on one side and two rings on the other side.

Exodus 28:12

28:12 You are to put the two stones on the shoulders of the ephod, stones of memorial for the sons of Israel, and Aaron will bear their names before the Lord on his two shoulders for a memorial.

Exodus 28:21

28:21 The stones are to be for the names of the sons of Israel, twelve, according to the number of their names. Each name according to the twelve tribes is to be like the engravings of a seal.

Exodus 34:4

34:4 So Moses cut out two tablets of stone like the first; early in the morning he went up to Mount Sinai, just as the Lord had commanded him, and he took in his hand the two tablets of stone.