鞍上人なく鞍下馬なし
あんじょうひとなくあんかうまなし
riding a horse so skillfully that it appears as if man and horse have become one
鞍下 is read as くらした (kurashita) and means sirloin (beef).
くらした
kurashita
あんじょうひとなくあんかうまなし
riding a horse so skillfully that it appears as if man and horse have become one