Passage 7.20.4
βουσὶ γὰρ χαίρειν μάλιστα Ἀπόλλωνα Ἀλκαῖός τε ἐδήλωσεν ἐν ὕμνῳ τῷ ἐς Ἑρμῆν, γράψας ὡς ὁ Ἑρμῆς βοῦς ὑφέλοιτο τοῦ Ἀπόλλωνος, καὶ ἔτι πρότερον ἢ Ἀλκαῖον γενέσθαι πεποιημένα ἦν Ὁμήρῳ βοῦς Ἀπόλλωνα Λαομέδοντος ἐπὶ μισθῷ νέμειν· Ποσειδῶνι περιέθηκεν ἐν Ἰλιάδι τὰ ἔπη,
That Apollo delights especially in cattle was stated clearly by Alcaeus in his hymn to Hermes, where he writes that Hermes stole Apollo's cattle. And even earlier than Alcaeus' time, Homer had composed that Apollo herded the cattle of Laomedon as payment, though in the Iliad he attributes these verses to Poseidon.