Valmiki Ramayana Ayodhya Kanda Sarga 24 Shloka 13

मे पिता my father, जगतीपतिः lord of the earth, काकुत्स्थः the descendant of Kakutstha, यावत् as long as, जीवति lives, तावत् till then, शुश्रूषा service, क्रियताम् be done, सः that one, धर्मः हि सनातनः it is eternal virtue.

As long as the king, my father, the lord of the earth, a descendant of Kakutshta lives, you shall serve him. This is eternal virtue (in a woman).