Valmiki Ramayana Aranya Kanda Sarga 16 Shloka 36
Original Shlokaइत्येवं लक्ष्मणे वाक्यं स्नेहाद्ब्रुवति धार्मिके। परिवादं जनन्यास्तमसहन्राघवोऽब्रवीत्।।3.16.36।।
1 source checked for this shloka
धार्मिके generous, लक्ष्मणे Lakshmana, स्नेहात् out of love, इत्येवम् in this way, वाक्यम् words, ब्रुवते as he was uttering, राघवः Rama, जनन्याः mother's, तम् him, परिवादम् censure, असहन् unable to tolerate, अब्रवीत् said.
When pious Lakshmana said thus to Rama out of his love for him, Rama replied, unable to tolerate the words of censure against mother (Kaikeyi) :