Epimerismi homerici ordine alphabetico traditi, alpha 142 (τὸ ἀργαλέος παρὰ τὸ ἄλγος μεταθέσει τοῦ λ εἰς ρ); Etym. Gudianum, alpha, p. 184 (idem); Etym. Symeonis 1, p. 166 (idem); Ps.-Zonaras, Lexicon, alpha, p. 286 (idem); Suda, alpha 3756 (Ἀργαλέον, χαλεπόν. εἴρηται δὲ ἀπὸ τοῦ ἄλγους, ἀλγαλέον καὶ τροπῇ τοῦ λ εἰς τὸ ρ); Etym. Magnum, Kallierges, p. 135 (Ἀργαλέος: Χαλεπός· οἶμαι παρὰ τὸν ἄρην, τὸν πόλεμον, ἀραλέος· καὶ πλεονασμῷ τοῦ γ, ἀργαλέος. Ἢ παρὰ τὸ ἄλγος, ὁ λύπας καὶ κακὰ ἐμποιῶν, μεταθέσει τοῦ λ εἰς ρ); ibid., p. 538 (κρίκος: […] Ἢ ὡς ἄλγος ἀλγαλέος καὶ ἀργαλέος); Eustathius, Comm. Il. 4.807 Van der Valk (Ἐτυμολόγοι τὸ ἀργαλέον οὐ μόνον ἀπὸ τοῦ ἔργου ἀλλὰ καὶ ἀπὸ τοῦ ἄλγους ἐτυμολογοῦντες εὑρίσκονται τροπῇ τοῦ λ εἰς ρ); Ps.-Zonaras, Lexicon, alpha, p. 286 (Ἀργαλέος. χαλεπὸς, δεινός. παρὰ τὸ τὸν ἄρην, τὸν πόλεμον, ἀραλέος, καὶ πλεονασμῷ τοῦ γ ἀργαλέος. ἢ παρὰ τὸ ἄλγος, ὁ λύπας καὶ κακὰ ἐμποιῶν); Moschopoulos, Scholia in Hesiodi Opera 484a (ἀργαλέος γὰρ ἀπὸ τοῦ ἄλγος); Scholia in Aristophanem, Plutus 1 (εἴρηται δὲ παρὰ τὸ ἄλγος ἀλγαλέον καὶ κατὰ τροπὴν τοῦ λ εἰς ρ ἀργαλέον […] ἀπὸ τοῦ ἄλγος ἀργαλέον ὡς ποδαλγία, ποδαργία); Scholia in Hesiodi Opera 227 (Ἐκ τοῦ ἔργου τὸ χαλεπὸν καὶ δυσχερὲς, ἐργαλέον, καὶ ἀργαλέον, Ἢ παρὰ τὸ ἄλγος, ἀλγαλέον, καὶ ἀργαλέον, Tzetzes); ibid. 480 (ἀργαλέος γὰρ ἀπὸ τοῦ ἄλγος).

The etymology might be much older: we may have an etymological figura in Homer, Il. 15.230 δεσμῷ ἐν ἀργαλέῳ δέδετο, κρατέρ’ ἄλγεα πάσχων "he was bound in a painful bond, suffering hard pains"