Phillip Wesley Comfort notes that P. Oxyrhynchus 4010 (late third/early fourth century) is the earliest papyri witness to a lack of a doxology after Matthew 6:13.
Philip Wesley Comfort, The Text of the Earliest New Testament Greek Manuscripts, 2 vols, 3rd ed. (Grand Rapids, MI: Kregel Academic, 2019), 2:208
P. Oxyrhynchus 4010
(not assigned a New Testament papyrus number)
Contents Introductory prayer followed by the Lord’s Prayer (Matt. 6:9-13)
Date late third or early fourth century
Housing location Oxford, England: Ashmolean Museum
Bibliography K. Treu, Oxyrhynchus Papyri LX, no. 4010, 5-7.
Textual character This manuscript was not given a Nestle-Aland papyrus number because it contains an introductory prayer before the Lord’s Prayer (Matt. 6:9-13). Nevertheless, it is the earliest witness (along with codices Vaticanus and Sinaiticus) not to include any kind of doxology after Matthew 6:13. Therein is its importance. This transcription will present only Matthew 6:0-13 (and not the introductory prayer)
. . .
13 κα[ι μη εισενεγκης ημας εις πειρασμον αλλα [ρυσαι ημας α πο του πονηρου ρυσαι ημ[ας