What is Paul longing to be clothed by in 2 Cor 5:4?

Question

2 Corinthians 5:4 (NASB)

For indeed while we are in this tent, we grown, being burdened, because we do not want to be unclothed but to be clothed, so that what is mortal will be swallowed up by life.

What is Paul longing to be clothed by?

Answer 1

2 Cor 5:1-4 says:

1 Now we know that if the earthly tent we live in is dismantled, we have a building from God, an eternal house in heaven, not built by human hands. 2 For in this tent we groan, longing to be clothed with our heavenly dwelling, 3 because when we are clothed, we will not be found naked. 4 So while we are in this tent, we groan under our burdens, because we do not wish to be unclothed but clothed, so that our mortality may be swallowed up by life.

This appears to be a direct allusion to what Paul discussed in 1 Cor 15:51-55 -

51 Listen, I tell you a mystery: We will not all sleep, but we will all be changed— 52 in an instant, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed. 53 For the perishable must be clothed with the imperishable, and the mortal with immortality. 54 When the perishable has been clothed with the imperishable and the mortal with immortality, then the saying that is written will come to pass: “Death has been swallowed up in victory.” 55 “Where, O Death, is your victory? Where, O Death, is your sting?”

The context of the 1 Cor 15 is definitely the resurrection at the second coming of Jesus (V35-49). Thus, we are to be "clothed" with immortal/imperishable bodies when we are made immortal at that time (V54).