The Old Testament Saints are part of Christ Body the Church, or they will not partake of the resurrection in the Last day which they had an eye to. Christ is the firstfruits 1 Cor 15:12-23
12 Now if Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead? 13 But if there be no resurrection of the dead, then is Christ not risen: 14 and if Christ be not risen, then is our preaching vain, and your faith is also vain. 15 Yea, and we are found false witnesses of God; because we have testified of God that he raised up Christ: whom he raised not up, if so be that the dead rise not. 16 For if the dead rise not, then is not Christ raised: 17 and if Christ be not raised, your faith is vain; ye are yet in your sins. 18 Then they also which are fallen asleep in Christ are perished. 19 If in this life only we have hope in Christ, we are of all men most miserable. 20 But now is Christ risen from the dead, and become the firstfruits of them that slept. 21 For since by man came death, by man came also the resurrection of the dead. 22 For as in Adam all die, even so in Christ shall all be made alive. 23 But every man in his own order: Christ the firstfruits; afterward they that are Christ’s at his coming.
Jesus Christ is the resurrection Jn 11:24-25
24 Martha saith unto him, I know that he shall rise again in the resurrection at the last day. 25 Jesus said unto her, I am the resurrection, and the life:
Paul testifies that the OT Fathers believed in the resurrection Acts 24:14-15
14 But this I confess unto thee, that after the way which they call heresy, so worship I the God of my fathers, believing all things which are written in the law and in the prophets: 15 and have hope toward God, which they themselves also allow, that there shall be a resurrection of the dead, both of the just and unjust.
Now the resurrection of the just, or Justified of all time is contingent upon being in Christ ! Its only in Him that all shall be made alive. That goes for King David, or the Philippian Jailor. 6