Ramayana
सन्ध्यायास्तनयां सो ऽथ सन्ध्यातुल्यां प्रभावतः । वरयामास पुत्रार्थं हेती राक्षसपुङ्गवः ॥ 7-4-20 ॥
Then Heti, that bull among rakshasas, sought for his son the daughter of Sandhya (Twilight), who in power was equal to Sandhya herself.
english translation