The verse of Veach Es Dimchem Lenafshoseichem Edrosh [i.e. suicide]:

Some Poskim[1] learn that the verse [Bereishis 9:5] of Veach Es Dimchem Lenafshoseichem Edrosh, speaking against Bnei Noach committing suicide, includes also a requirement to guard one’s life from dangers, and hence one who enters himself to a dangerous situation transgresses this command. However, this verse is omitted from most Poskim [including Admur, the Michaber and Rambam], as a source for the obligation to guard one’s health and only the previous verse of “Hishamer” is recorded. The reason for this because the simple meaning of this verse refers to the actual intentional commitment of suicide and not to simply endangering oneself.[2] However, seemingly the prohibition for one to intentionally injure his body through hitting it or fasting seemingly derives from this verse.[3] However, some Poskim[4] learn also this prohibition against self-affliction from the previous verse of “Hishamer”

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[1] Sefer Chassidim 675; Levush Y.D. 116:1; Shoel Umeishiv Tinyana 3:122; Aruch Hashulchan Y.D. 116:1; See Encyclopedia Talmudit Erech “Miabeid Atzmo Ladaas” Vol. 38

[2] Shem Aryeh Y.D. 27 based on Bava Kama 91b; Peri Chadash in Mayim Chaim on Shavuos 36

[3] See Admur Hilchos Nizkeiy Guf Vinefesh Halacha 4; Torah Temima on verse ibid; See Halacha 3

[4] Binyan Yehoshua on Avos Rebbe Nasan 3:4; Urim vetumim 27:1; Aruch Hashulchan C.M. 420:43’ Kuntrus Likkutei Imrim 13 of Chofetz Chaim