William Burkitt on Revelation 3:21

Here our Saviour concludes this epistle, as he did the former, with a promise to the persevering Christian, To him that overcometh, namely, all the trials and temptations of this life, and keeps his faith, love, and obedience, entire to the end, I will grant, not in a way of merit, but of free gift and grace, to sit down with me in my throne, namely, to partake of the same power, and glory, and kingdom, that I as Mediator do now partake of.

Where observe, Christ here distinguishes between his own throne and his Father's; the former seems to be his mediatorial,the latter his essential, throne; and he plainly tells us, that as he obtained his glory by overcoming Satan and the world, so must we; To him that overcometh will I grant-- even as I also overcame: the way to heaven for Christ and all his members is the same; as he conquered and finally overcame on earth before he was crowned in heaven, so must they.