The Seven Labours of Rostam were a series of acts carried out by the greatest of the Iranian heroes, Rostam, The story was retold by Ferdowsi in his epic poem, Shahnameh.
In fact, in this Labour, the Rostam’s horse (Rakhsh) kills a lion with his teeth. Rostam falls asleep among the reeds. After a short time, a fierce lion appears, and mounts a ferocious attack on his horse Rakhsh; but Rakhsh, although hard-pressed, succeeds in killing the savage beast with his teeth.