Exodus 27:1 - Joseph Benson’s Commentary on the Old and New Testaments

Thou shalt make an altar As God intended in the tabernacle to manifest his presence among his people, so there they were to pay their devotions to him; not in the tabernacle itself, into that only the priests entered as God's domestic servants, but in the court before the tabernacle, where, as common subjects, they attended. There an altar was ordered to be set up, to which they must bring their sacrifices; and this altar was to sanctify their gifts; from hence they were to present their services to God, as from the mercy-seat he gave his oracles to them: and thus a communion was settled between God and Israel. This altar was placed at the entrance of the sanctuary, and is termed the altar of burnt-offering, and the great altar: it was almost three yards square, and above a yard and a half in height. It was made of wood rather than of solid brass, that it might not be too heavy. But notwithstanding that it was overlaid with brass, (Exodus 27:2,) had it been of common wood, it must soon have been consumed to ashes by the continual heat: hence Le Clerc conjectures that this shittim-wood might be the larch-tree, which bears the fire like stone.