Ramayana
मातृष्वसुरथास्माकं सा च कन्या ऽनलोद्भवा । भवत्यस्माकमेवैषा भ्रातृणां धर्मतः स्वसा ॥ 7-25-24 ॥
She was thus the daughter of our mother's sister, a maiden sprung from the fire; by dharma she is therefore the sister of us brothers.
english translation