he didn't apollo traded Hermes the cattle for his lyre.
Apollo had a golden bow with golden arrows to match.
Hermes exchanged the lyre for Apollo's cattle.
First of, it's not a harp, it's a lyre. Second, Hermes made it for him. Kinda. Hermes stole Apollo's cattle, then took a tortoise, and made a lyre out of it. Apollo found Hermes, saw the lyre, heard how beautiful it sounded and traded his golden wand, the Caduceus for it.
Hermes gave Apollo the lyre in trade for the Apollo's cattle that Hermes stole
He stole Apollo's cattle and slaughtered two cows.
The Greeks associated the lyre with Apollo. Hermes actually created it, but after he stole Apollo's cattle and was arguing with him, Hermes started to play the lyre. Apollo was so entranced that he traded the cattle for the lyre.
the sun god Apollo
He stole Cattle from Apollo.
21
Shortly after he was born, Hermes invented the lyre. A bit after that, he stole cattle from Apollo. Apollo agreed to give Hermes the cattle in exchange for the lyre.
They are brothers, and when Hermes was born he stole the cattle Apollo was supposed to be watching over.