In the modern critical editions, and in the (outdated and woefully inaccurate) assessment of Samuel Davidson above, we find Origen among the evidence listed for qui (Gr. ὅς), which is "who" in English. This is incorrect. The statement in question occurs in his Commentary on Romans (1.4.1): De quibus quamvis periculosum videatur chartulis committere sermonem, tamen non otiose praetereunda sunt dicta sapientium et aenigmata, sed subtili admodum mentis acie, in quantum res patitur, velut per quoddam speculum contemplanda: ne forte is qui Verbum caro factus apparuit positis in carne, sicut Apostolus dicit quia manifestatus est in carne, justificatus in spiritu, apparuit angelis &c.

The word in question is not the relative pronoun, qui ("who") but rather a Late Latin subordinator, quia ("that"). The verb manifestatus ("he-was-manifest") directly references is qui Verbum caro factus. That is, “Though it may seem perilous to commit [such] words to paper, yet they are not to be idly passed over, the sayings and riddles of the wise, but with very subtle keenness of the mind, insofar as circumstances permit, as though contemplating in a mirror: that He who is the Word made flesh,” i.e., God, “appeared to those who were in the flesh, even as the Apostle says that He [the Word] ‘was manifest in the flesh, justified in the Spirit’ [and] ‘seen of angels.’” In more ancient Christian writings John 1:1, 14 and 1 Timothy 3:16 are frequently intertwined in commentary.

Ben David and John Burgon (briefly, see also p. 448) above rightly assess the situation. The reason for attributing the reading qui (“who”) to Origen stems from the suggestion by Wetstein, who was followed by Griesbach (1806),[1] Henry Alford (1865)[2], F.J.A. Hort (1882),[3] Philip Schaff (1882)[4] et al that qui (“who”) should be read in place of quia. Ultimately Schaff, in 1863, reified this conjecture and proclaimed that Origen in Latin indeed reads qui manifestatus est.[5] Origen has been incorrectly listed among the evidence for qui ever since.

Minuscule 1739 (9th century) was produced from a second or third century exemplar that remained in use until about the 4th century, and contains a colophon indicating it was copied from a text edited by Origen in the Pauline Epistles. The reading contains the Euthalian header "On the divine incarnation" and the reading is "God was manifest in the flesh."

[1] “Griesbach—Nov. Testamentum Grace, Vol. II”, The Monthly Review, vol. LIII, [1807] p. 505.
[2] Henry Alford, The Greek Testament: with Various Readings, [Deighton, Bell, and Co., Cambridge, 1865] p. 333
[3] Fenton John Anthony Hort, The New Testament in the Original Greek: Introduction. Appendix [Macmillan and Company, 1882], Appendix I: Notes on Select Readings, p. 133
[4] Philip Schaff, The New Testament in the original Greek, [Harper & Brothers, 1882] vol. 2, p. 133: “Orig.Rom.lat.Ruf(sicut apostolus dicit Quia [? Qui] manifestatus est in carne &c.)”.
[5] Philip Schaff, A Companion to the Greek Testament and the English Version, [Harper & Brothers, 1883] p. 200: “Origen (qui manifestatus est)”.