Valmiki Ramayana Kishkindha Kanda Sarga 16 Shloka 33

ततः then, आशीविषोपमम् poisonous like a snake, शरम् arrow, धनुषि at the bow, सन्धाय having fixed, अन्तकः lord of death, कालचक्रमिव like the wheel of death, तत् चापम् that bow, पुरयामास stretched at fully.

Rama then fixed an arrow which resembled a venomous snake, on to his bow looking like the very deathwheel of Yama and stretched it fully.