"Today you shall be with me in Paradise."
That was a promise, with fulfilled forgiveness yet in the offing.
While Paradise (Abrahsm's Bosom) was yet an adjunct segment of Hell (Hades). it was two days later that Jesus successfully offered His sacrificial blood, slaked The God's anger with mankind, and obtained The Father's permission to detach Paradise (which had been, though pleasant, a place of captivity of souls believing in Messiah) from Hades, and merge it with Heaven instead,
Ephesians 4:8-10 AV:
8 Wherefore he saith, When he ascended up on high, he led captivity captive,
and gave gifts unto men.
9 (Now that he ascended, what is it but that he also descended first into the lower
parts of the earth?
10 He that descended is the same also that ascended up far above all heavens,
that he might fill all things.)
Because of Jesus' Blood atonement at the Mercy Seat of Heaven, all these OT saints were finally able to be admitted to Heaven forever, fulfilling His promise to them.