Negative commandment · Lo Ta’aseh #33 of 613
Not to act as a soothsayer
שלא לנחש
The verse · Vayikra 19:26
לֹא תֹאכְלוּ עַל־הַדָּם לֹא תְנַחֲשׁוּ וְלֹא תְעוֹנֵנוּ
“You shall not eat anything with the blood: neither shall you use enchantment, nor observe times.”
The Rambam’s words
Not to act as a soothsayer, as [Leviticus, ibid.] states: "Do not act as a soothsayer."
שלא לנחש, שנאמר "לא תנחשו" (ויקרא יט,כו).
Why · Sefer HaChinuch #249
To not divine
“It is from the roots of the commandment [that it is] because these matters are crazy things and total foolishness; and it is not fitting for the holy true people that G-d chose that they pay attention to false words.”
Who & when
“And [it] is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Foreign Worship and Customs of the Nations הלכות עבודה זרה וחוקות הגויים