Valmiki Ramayana Ayodhya Kanda Sarga 13 Shloka 7
Original Shlokaकैकेय्याः प्रियकामेन रामः प्रव्राजितो मया। यदि सत्यं ब्रवीम्येतत्तदसत्यं भविष्यति।।2.13.7।।
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कैकेय्याः of Kaikeyi, प्रियकामेन for the pleasure, मया by me, रामः Rama, प्रव्राजितः was sent (to the forest), एतत् this, सत्यम् truth, ब्रवीमि यदि if I tell, तत् that, असत्यम् untruth, भविष्यति will become.
If I tell the truth, 'To please Kaikeyi I have sent Rama to the forest', none will believe it and will consider it untruth.