The Lord commanded Moses to tell the Israelites: "You have seen how I, the Lord, have spoken to you from heaven.
Do not make for yourselves gods of silver or gold to be worshiped in addition to me.
Make an altar of earth for me, and on it sacrifice your sheep and your cattle as offerings to be completely burned and as fellowship offerings. In every place that I set aside for you to worship me, I will come to you and bless you.
If you make an altar of stone for me, do not build it out of cut stones, because when you use a chisel on stones, you make them unfit for my use. 1
References for Exodus 20:25
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.