For we that are in this tabernacle do groan, being burdened: not for that we would be unclothed, but clothed upon, that mortality might be swallowed up of life. For we that are in this tabernacle - We who are in this state of trial and difficulty do groan, being burdened; as if he had said: The whole of human life is a state of suffering, and especially our lot; who are troubled on every side, perplexed, persecuted, cast down, bearing about in the body the dying of our Lord Jesus, and being always delivered unto death on the account of Jesus, 2 Corinthians 4:8-11. These were sufficient burdens, and sufficient causes of groaning.
Not for that we would be unclothed - We do not desire death, nor to die, even with the full prospect of eternal glory before our eyes, an hour before that time which God in his wisdom has assigned.
But clothed upon - To have the fullest preparation for eternal glory. We wish not to die, whatever tribulation we may be called to pass through, till the whole will of God is accomplished in us and by us.
That mortality might be swallowed up of life - Being fully prepared for the eternal state we shall scarcely be said to die, all that is mortal being absorbed and annihilated by immortality and glory. See the notes on 1 Corinthians 15:51-56 (note). From the use of these expressions among the Jews, this seems to be the general meaning of the apostle.