John Gill Commentary Ezekiel 1:26

"And above the firmament that was over their heads was the likeness of a throne, as the appearance of a sapphire stone; and upon the likeness of the throne was a likeness as the appearance of a man upon it above." — Ezekiel 1:26 (ASV)

And above the firmament that [was] over their heads
The heads of the living creatures: [was] the likeness of a throne ;

a symbol of Christ's kingly power and authority, who is the person that sat upon it; as he is God, he is on the same throne with his Father; as Mediator, he is King of saints, and was so from eternity; he exercised his office before his incarnation; and as he was prophesied of as a King, he came as one, though little known, and his kingdom was not with observation; upon his ascension he was declared Lord and Christ; and will appear on a throne, when he shall come to judge the world, and particularly in the New Jerusalem church state:

and this throne was as the appearance of a sapphire stone ;
which is a stone very clear and transparent; very hard, solid, and durable; very precious and excellent; and of an azure sky colour; denoting the clear manifestation of Christ's righteous judgments, in the ministration of his kingly office; the duration of his government; the excellency of it; and its heavenly nature and original:

and upon the likeness of the throne [was] the likeness of the
appearance of a man above upon it ;
this was no other than Christ; who, though he was not really man before his incarnation, yet often appeared in the form of a man; and, through his incarnation, he was found in fashion as a man; and was really man, though not a mere man; nor was the person here designed; for that was the appearance and likeness of the glory of the Lord, (Ezekiel 1:28) ; and this shows, that when Christ, as man, had done his work, he should sit down upon his throne above the firmament, being made higher than the heavens,