Canto 3 -
Araṇya-kāṇḍa
Chapter 43: Sītā Sees the Magical Deer
Text 3.43.19

जीवन्न यदि तेऽभ्येति ग्रहणं मृगसत्तमः।
अजिनं नरशार्दूल रुचिरं मे भविष्यति॥

jīvan na yadi te ’bhyeti grahaṇaṁ mṛga-sattamaḥ
ajinaṁ nara-śārdūla ruciraṁ me bhaviṣyati

jīvan = while it is alive; na = not; yadi = if; te = Your; abhyeti = does come; grahaṇam = under grasp; mṛga-sattamaḥ = [this] excellent deer; ajinam = [its] skin; nara-śārdūla = O prince; ruciram = pleasing; me = to me; bhaviṣyati = will be.

If [this] excellent deer does not come under Your grasp while it is alive, O prince, [its] skin will be pleasing to me.

She elaborates on its pleasant nature in the next verse.