There is not a passage that directly mentions the "Old Testament" saints, however, the Apostle Paul wrote, 

"we are of good courage, I say, and prefer rather to be absent from the body and to be at home with the Lord." (2 Cor 5:8)

We also know that Moses and Elijah appeared with Jesus when He was transfigured (Matt 27:2-3) and that Jesus told the thief on the cross, "today you shall be with Me in Paradise" (Luke 23:43).

From these statements, it is clear that the faithful departed are presently with the Lord.