Today in paradise
Whether 'today' attaches to the promise or to the speaking, and where the thief goes at death.
Luke 23:39-43
39One of the criminals who was hanged insulted him, saying, “If you are the Christ, save yourself and us!”
40But the other answered, and rebuking him said, “Don’t you even fear God, seeing you are under the same condemnation?
41And we indeed justly, for we receive the due reward for our deeds, but this man has done nothing wrong.”
42He said to Jesus, “Lord, remember me when you come into your Kingdom.”
43Jesus said to him, “Assuredly I tell you, today you will be with me in Paradise.”
What each tradition says
Rabbinic / Midrashic
No sourced position found. Checked the Jewish Encyclopedia 1905 (jewishencyclopedia.com): its articles "Revelation (Book of)", "Eschatology" and "Messiah" do not treat Luke 23:39-43 or the thief's promise, and web searches restricted to jewishencyclopedia.com for "thief" / "paradise" / Luke 23:43 returned no article; Sefaria's texts API covers only the Jewish canon (no New Testament commentary). No public-domain rabbinic/midrashic statement on this verse dispute found.
Patristic
Tertullian states that every soul is detained in safe keeping in Hades until the day of the Lord. He presents this as the established position.
Tertullian, A Treatise on the Soul (De Anima), ch. LV — ANF vol. 3 (ed. Roberts & Donaldson) — Ch. LV, "The Christian Idea of the Position of Hades; The Blessedness of Paradise Immediately After Death. The Privilege of the Martyrs"
Catholic
Witham says the promise means, "This day thou shalt be with me in Paradise," a place of rest with the souls of the just. He explains the construction is not "I say to thee this day," but "thou shalt be with me this day in the paradise."
George Leo Haydock (citing Witham), George Haydock's Catholic Bible Commentary (1859) — On Luke 23:43 (Witham's note)
Orthodox
Cyril of Jerusalem teaches that whoever believes Jesus Christ is Lord and that God raised Him from the dead will be saved and transported into Paradise by Him who brought the robber there. He who saved the robber on Golgotha after one hour of belief will likewise save the one who believes.
Cyril of Jerusalem, The Catechetical Lectures of S. Cyril, Lecture V ("Of Faith") — NPNF 2nd series, vol. 7 — Lecture V, §10 (on faith worked in a single hour, the robber brought into Paradise)
Reformed / Protestant
Calvin says, on the words "Today shalt thou be with me in paradise," that curious and subtle arguments about the place of paradise are to be avoided. Those engrafted by faith into Christ's body partake of that life, and after death enjoy blessed and joyful rest until Christ's coming fully manifests the perfect glory of heavenly life.
John Calvin, Commentary on Matthew, Mark, Luke, vol. 3 (Harmony of the Evangelists; Calvin Translation Society) — On Luke 23:43
Evangelical
John Wesley identifies paradise as the place where the souls of the righteous remain from death until the resurrection. He reads Jesus' promise as meaning that the thief would not only be remembered then, but on that very day.
John Wesley, John Wesley's Explanatory Notes on the New Testament — On Luke 23:43 (note on "In paradise")