Q: What benefits do believers receive from Christ at death?
A: The souls of believers are at their death made perfect in holiness, and do immediately pass into glory; and their bodies, being still united to Christ, do rest in their graves till the resurrection.

Luke 23:43. And Jesus said unto him, Verily I say unto thee, To day shalt thou be with me in paradise.
Luke 16:23. And in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom.
Philippians 1:23. For I am in a strait betwixt two, having a desire to depart, and to be with Christ; which is far better.
2 Corinthians 5:6-8. Therefore we arealways confident, knowing that, whilst we are at home in the body, we are absent from the Lord: (for we walk by faith, not by sight:) we are confident, I say, and willing rather to be absent from the body, and to be present with the Lord.
1 Thessalonians 4:14. For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him.
Romans 8:23. And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body.
1 Thessalonians 4:14. For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him.

Westminster Project - Read Thomas Watson's sermon on the Believer's privilege at death