Deuteronomy 27:5
Build an altar there to Jehovah your God. Build the altar of stones. Do not use an iron tool on them.
Exodus 20:25
If you make an altar of stone for me, do not build it out of cut stones. This is because when you use a chisel on stones, you make them unfit for my use.
Exodus 24:4
Moses wrote down all Jehovah's words. Early the next morning he built an altar at the foot of the mountain. He erected twelve sacred stones for the twelve tribes of Israel.
Joshua 8:30-31
Then Joshua built an altar to Jehovah the God of Israel on mount Ebal,
1 Kings 18:31-32
Elijah took twelve stones, the number of the tribes of the sons of Jacob, to whom Jehovah said: Israel will be your name.