The possibly spurious line is 2.191:
πρῆξαι δ᾽ ἔμπης οὔ τι δυνήσεται εἵνεκα τῶνδε:
and he will in no case be able to do aught because of these men here
Homer. Odyssey 2.191. Translated by A. T. Murray (1919). Perseus Digital Library.
The reason why the line is considered spurious is that it is omitted from some manuscripts of the poem. According to Hayman these include the “best” manuscripts:
The line 191, not found in many of the best copies, is probably from Il. (mar.)†
Henry Hayman (1866). The Odyssey of Homer, volume 1, p. 45, note to Β.191. London: David Nutt.
† That is, a marginal note in one of the manuscripts says that the line comes from the Iliad. See below.
For the details of which manuscripts, we need a critical edition, for example, that of Allen:
191 om. a g i k o Eust. (cf. Α 562) εἵνεκα τῶνδε p r: οἷος ἀπ᾿ ἄλλων cet.
Thomas W. Allen (1908). Homeri Opera, volume 3, note to Β.191. Oxford: Clarendon Press.
Here the bold letters a to s are the families of manuscripts of the Odyssey, listed by Allen on page xiii. For example, family a consists of manuscripts C (Caesenas 27.11, before 1311), L7 (Laurentianus 91, 13th century) and R4 (Vaticanus 915, 13th century). So Allen’s note says that line 2.191 is omitted from families a g i k o, and from the 12th-century commentary of Eustathius of Thessalonica. The words εἵνεκα τῶνδε (“on account of these”) at the end of the line occur in families p and r. All the other manuscripts have οἷος ἀπ᾿ ἄλλων (“because of the others”) instead.
The note “cf. Α 562” invites us to compare Odyssey 2.191 with Iliad 1.562, which has identical wording in the first part of the line:
πρῆξαι δ᾽ ἔμπης οὔ τι δυνήσεαι, ἀλλ᾽ ἀπὸ θυμοῦ
yet you shall be able to accomplish nothing, but shall be even further from my heart
Homer. Iliad 1.562. Translated by A. T. Murray (1924). Perseus Digital Library.
The manuscript evidence does not prove by itself that the line is spurious: the evidence could be explained just as well by the line being omitted from an ancestor of manuscript families a g i k o as by its being added to an ancestor of the other families. However, Merry and Riddell criticize the line on rhetorical grounds, because it intrudes a reference to the suitors into the antithesis between Eurymachus’ pity for Telemachus and scorn for Halitherses:
191. εἵνεκα τῶνδε. If we have to attempt an interpretation of a spurious line, this phrase may mean ‘because of the [resistance of] these suitors here.’ But “τῶνδε”† is an unsatisfactory equivalent for “ἡμέων”.‡ Perhaps we might render ‘by help of all these omens’ of thine. Not only is the verse deficient in authority, but it spoils the antithesis between “αὐτῷ μέν οἱ” and “σοὶ δέ”.§
W. Walter Merry & James Riddell (1886). Homer’s Odyssey, volume 1, p. 69, note to Β.191. Oxford, Clarendon Press
† τῶνδε = “these men here” in A. T. Murray’s translation, interpreting the word as referring to the suitors of Penelope. ‡ ἡμέων means “for us at least” or “on our part” and is used in the singular, ἐγὼ, by Eurymachus at line 194. § αὐτῷ μέν οἱ = “for him in the first place”; σοὶ δέ = “and on thee” (A. T. Murray).
Another argument for 2.191 being spurious is that there are no Greek scholia on the line. If it had appeared in the ancient manuscripts, we would expect a scholiast to have referred us to the similar line from the Iliad, or to have glossed τῶνδε as referring to the suitors.