Valmiki Ramayana 7.86.15

यो ऽयमंशस्तृतीयो मे स्त्रीषु यौवनशालिषु ।त्रिरात्रं दर्पपूर्णासु वशिष्ये दर्पघातिनी॥

yo 'yamaṃśastṛtīyo me strīṣu yauvanaśāliṣu |trirātraṃ darpapūrṇāsu vaśiṣye darpaghātinī ||

Our plain-language meaning of this verse is waiting for scholar review.