Valmiki Ramayana Yuddha Kanda Sarga 38 Shloka 7

एकः one alone, कालपाशवशम् fallen into the noose of death, गतः gone, पापम् sin, कुरुतेहि has done also, नीचेन meanly, तेन because of that, आत्मापचारेण because of his own mistake, कुलम् race, विनश्यति will perish.

"Only one has done that sin and fallen into the noose of death. Because of one Rakshasa's mistake the race will perish."