Valmiki Ramayana Bala Kanda Sarga 20 Shloka 25
Original Shlokaअथ कालोपमौ युध्दे सुतौ सुन्दोपसुन्दयो:।।1.20.25।। यज्ञविघ्नकरौ तौ ते नैव दास्यामि पुत्रकम्।
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अथ and, ते you, यज्ञविघ्नकरौ those causing obstacles to sacrifice, सुन्दोपसुन्दयो: of Sunda and Upasunda, सुतौ तौ sons, युध्दे in the battle, कालोपमौ resemble god of death, Yama, पुत्रकम् my son, नैव दास्यामि I shall never part with him.
Further the sons of Sunda and Upasunda by name Maricha and Subahu are causing obstacles to your sacrifice. They resemble the god of death, Yama. I shall never part with my son.