Ramayana
यद्वा ऽमृतरसः पीतस्त्वया रावण राक्षस । तदा वालिनमासाद्य तदन्तं तव जीवितम् ॥ 7-34-8 ॥
Or even if indeed you have drunk the nectar of immortality, O Rakshasa Ravana, then, upon encountering Vali, that will be the end of your life.
english translation