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SB 10.50.18

tava rāma yadi śraddhā
 yudhyasva dhairyam udvaha
hitvā vā mac-charaiś chinnaṁ
 dehaṁ svar yāhi māṁ jahi
tava — Your; rāma — O Balarāma; yadi — if; śraddhā — confidence; yudhyasva — fight; dhairyam — courage; udvaha — take up; hitvā — leaving aside; — either; mat — my; śaraiḥ — by the arrows; chinnam — cut to pieces; deham — Your body; svaḥ — to heaven; yāhi — go; mām — (or else) me; jahi — kill.
You, Rāma, should gather Your courage and fight with me, if You think You can do it. You may either give up Your body when it is cut to pieces by my arrows, and thus attain to heaven, or else kill me.

According to ācārya Śrīdhara Svāmī, Jarāsandha suspected that Lord Balarāma’s body was indestructible, and thus he offered what might be a more practical alternative, that Balarāma kill Jarāsandha.