DEUT666 Do not make incisions on your skin as a sign of grief over the dead. … our nation was chosen by Hashem to possess His Torah. In that we possess His precious wisdom as embodied by the Torah, it is not fitting that we be grief-stricken by any of His deeds. We are to mourn death only in the manner prescribed in His Torah [See [[LEV868]] Leviticus 21:2 impure CHINUCH 168-9], but to act like fools and intentionally hurt ourselves and damage our bodies is forbidden. Such is not the way of the wise and the understanding. Such practices are for ignoramuses and lowly people who know nothing of Hashem's ways and wondrous deeds.