And be found in Him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith… – Philippians 3:9

Many a time the question has been asked: “What was the wedding garment?” It is a question which need not be curiously pried into. So many answers have been given that I conclude that if our Saviour had intended any one specific thing He would have expressed Himself more plainly, so that we would have been able, without so much theological disputing, to have understood what He meant. It seems to me that our Lord intended much more than any one thing. The guests were bidden to come to the wedding to show their respect to the king and prince; some would not come at all, and so showed their sedition; this man came, and when he heard the regulation, that a certain garment should be put on, comely in appearance and suitable for the occasion, he determined that he would not wear it. In this act of rebellion, he went as far in opposition as they did who would not come at all, and he went a little further, for in the very presence of the guests and of the king he dared to declare his disloyalty and contempt. Alas, how many are willing enough to receive gospel blessings, but they are still at enmity with God and have no delight in the only Begotten Son. Such will dare to use the forms of godliness, and yet their hearts are full of rebellion against the Lord. The wedding garment represents anything which is indispensable to a Christian, but which the unrenewed heart is not willing to accept; anything which the Lord ordains to be a necessary attendant of salvation, against which selfishness rebels. Hence it may be said to be Christ’s righteousness imputed to us, for alas, many nominal Christians kick against the doctrine of justification by the righteousness of the Saviour and set up their own self-righteousness in opposition to it. To be found in Christ, not having our own righteousness, which is of the law, but having the righteousness which is of God by faith, is a very prominent badge of a real servant of God, and to refuse it is to manifest opposition to the glory of God, and to the name, person, and work of His exalted Son. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0976.cfm