Exodus 30:3

Thou shalt overlay it with pure gold. — Next to the Ark of the Covenant the most holy article of furniture contained either in the sanctuary or in its court was the altar of incense. It symbolised prayer in its general use (Psalms 141:2; Luke 1:10), and it symbolised expiation in the purpose whereto it was to be applied on certain occasions, as when the high priest had sinned in his official capacity (Leviticus 4:3), or when the whole congregation had sinned through inadvertence (Leviticus 4:13). It was, therefore, “most holy to the Lord.” Hence, its materials were to be the same with those of the ark of the covenant, and its place was to be directly opposite the ark, near to it, but on the outer side of the vail (Exodus 40:5).

A crown of gold round about. — Comp. what is said of the table of shewbread (Exodus 25:24). In both cases a raised rim or edging is meant, which would prevent what was on the top from falling off.