Valmiki Ramayana Ayodhya Kanda Sarga 21 Shloka 59

सः that kind of me, पितुः father's, सकलाम् completely, इमां प्रतिज्ञाम् this promise, यथावत् as it is, अकर्तुम् not to execute, न शक्नोमि वै for sooth I am not competent, तात O my dear, सः he, नियोगे in command, आवयोः for both of us, गुरुः हि is preceptor, देव्याश्च of mother also, सः he, भर्ता husband, सः he, गतिः is refuge, धर्मः virtue.

It is impossible for me not to execute the promise completely, O my dear, he (Dasaratha) is our preceptor and, therefore, fit to command us. Even for mother Kausalya, he is her husband, her refuge and her dharma.