Valmiki Ramayana Sundara Kanda Sarga 13 Shloka 36

वानराः vanaras, विषम् poison, उद्बन्धनं वापि or by hanging, ज्वलनस्य in the fire, प्रवेशं वा entering, उपवासम् by fasting, अथो or, शस्त्रम् weapon, प्रचरिष्यन्ति they will use to put an end.

"The vanaras will put an end to their lives by poisoning or by hanging or by selfimmolation or by killing themselves with weapons or by fasting unto death.