What is the verse about casting our crowns before the feet of Jesus?

Here too remark, it is not, as in the first chapter, the God who is, though embracing past and future, God in Himself; but the God of ages, "who was, and is, and is to come." Still He has all Old Testament names: Jehovah, Elohim, Shaddai. His attributes now celebrate His full name, as the Holy One who lives for ever and ever — has no passing power or being, like man at his best estate, vanity. And the saints here fall down before the throne, bow themselves before His place in glory, and worship Him in His endless being, and lay down their given glory before His supreme and proper glory, ascribing all glory to Him alone, as alone worthy of it; but here, according to the nature of the celebration of it, the Creator for whom all things are. In all changes these remained true.

It will be observed that in the declaration of the living creatures we have glory, honour, and thanks; in that of the elders it is glory, honour, and power. Further, the elders fall down before HIM Whom they love and reverence, and cast their crowns before the THRONE in the recognition of that from which their royal dignity is derived and sustained.*

On the other hand, when God in His holiness is celebrated by the four living creatures according to His own nature — when they praise Him as the "Holy, holy, holy, Lord God Almighty," the elders are at once in movement. Thus before judicial dealings the elders show us the most perfect rest in the presence of God. As a question of judgment there is not one demand of righteousness that was not satisfied by the cross. If there had been any sin unremoved, oh, what trouble had been among all the twenty-four! But no; they sit in perfect peace on their thrones. But when His holiness is in question, they fall down before Him; they do homage to Him that lives to the ages of ages; they cast their crowns before the throne. Their hearts are swallowed up in the delight of what God is. What He is in His holiness draws them out. It is the attractive power of His holiness, not the (to others) alarming power of the righteous judgments of God, which kindles their spirits and engages them in adoration. In the presence of righteousness there is nothing but rest; in the presence of the celebration of His holiness there is activity of worship.

It is to be remarked that there is dead silence as to angels in our chapter, whereas they distinctly appear in Rev. 5:2, 11, 12. This suggests what solves the difficulty often and largely felt. For the living creatures in themselves present the attributes of providential power in the execution of judgment; but the comparison of the chapters points to change in its administration from the angels who are now the agents to the redeemed who are to be. Hence in Rev. 4 the angels are merged as it were in the living creatures; in Rev. 5 they are distinguished in view of Christ's co-heirs, to whom and not to angels God will subject the inhabited earth to come (Heb. 2). The rendering of "beasts" in this case is still more unhappy than the belittling of "thrones" into "seats." It is quite a different word in Rev. 6:8 literally, and elsewhere symbolically.

And beautiful it is to see that, as often observed, the elders sat unmoved on their thrones before the judicial display of God's glory, and the signs of His displeasure in the lightnings and voices and thunders which went forth from His throne, with all other solemn tokens of coming judgment. But when the living creatures give glory and honour and thanksgiving to Him that sits on the throne, that lives for ever and ever, the elders fall and pay homage, and cast their crowns before the throne, saying, Worthy art thou, our Lord and our God, to receive the glory and the honour and the power; because thou didst create all the things, and for (or, on account of) thy will they were and were created. It was not only worship, but in full spiritual intelligence. Those that are a new creation in Christ enter into God's rights as Creator; which earth's inhabitants, and especially apostate Christians, are about to dispute and deny. Their zeal is in due season and character. For God's will the whole was in being, as it was also created.

The proclamation of God's holiness draws forth the worship of the elders. "And when those living creatures give glory and honour and thanks to Him that sat on the throne, who lives for ever and ever, the four and twenty elders fall down before Him that sat on the throne, and worship Him that lives for ever and ever, and cast their crowns before the throne, saying, Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created" [or "were and have been created"]. (vv. 9-11.) This is not worship addressed to the Father, but to the God of creation and providence. In this chapter Jesus is never separately named or seen. Yet in creation He is the person of the Godhead who actively works; for "all things were created by him and for Him; and He is before all things, and by Him all things consist." (Col. 1:16-17.) It is not, then, the Father, as distinct from the Son, that is here the object of adoration, but God, the Creator, including Father, Son, and Spirit. All creature glory is merely derived, and the elders, though crowned, and even associated with God in judgment, fall down and worship the ever-living One, casting their crowns before the throne, and owning that He only is worthy of honour, glory, and power; for by Him and for Him all things exist and were created.