Ramayana
अवध्या मम ते देवाः सुकेशतनया रणे । मन्त्रं तु वः प्रदास्यामि यस्तान्वै निहनिष्यति ॥ 7-6-29 ॥
Those sons of Sukesha cannot be slain by me in battle, O gods; but I shall give you a counsel by which one shall indeed destroy them.
english translation