John Wesley on Exodus 20:24

An altar of earth - It is meant of occasional altars, such as they reared in the wilderness before the tabernacle was erected, and afterwards upon special emergencies, for present use. They are appointed to make these very plain, either of earth or of unhewn stones. That they might not be tempted to think of a graven image, they must not so much as hew the stones into shape, that they made their altars of, but pile them up as they were in the rough. In all places where I record my name - Or where my name is recorded, that is, where I am worshipped in sincerity, I will come unto thee, and will bless thee.