Exodus 20:22-26 - Instructions For Building Altars
22 Jehovah commanded Moses to tell the Israelites: You have seen how I have spoken to you from heaven. 23 Do not make for yourselves gods of silver or gold to be worshiped in addition to me.
24 Make an altar of earth for me. Sacrifice your sheep and your cattle as offerings to be completely burned and as peace offerings. In every place that I set-aside for you to worship me, I will come to you and bless you. 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. 26 Do not build an altar for me with steps leading up to it. If you do, you will expose yourselves as you go up the steps.