Valmiki Ramayana Yuddha Kanda Sarga 5 Shloka 19
Original Shlokaकदानुराक्षसेन्द्रस्यनिधायोरसिसायकान् । सीतांप्रत्याहरिष्यामिशोकमुत्सृज्यमानसम् ।।6.5.19।।
1 source checked for this shloka
राक्षसेन्द्रस्य: rakshasa king's, निधायोरसि: into the chest, सायकान्: arrows, सीतां: Sita, प्रत्याहरिष्यामि: will get back, शोकमुत्सृज्य: casting off grief, मानसम्: from my mind, कदानु: indeed
Indeed by shooting arrows into the chest of rakshasa king, when will I get back Sita and cast off grief from my mind.