לא יהיה לך אלקים אחרים על פני
שמות כ ג
Don't believe in any 'god' besides Hashem Yisborach
One who accepts upon himself another 'god' or serves him in the way that that 'god' is generally served. In addition, by bowing to it, slaughtering for it, sacrificing [burning] to it, serving a libation to it or by spraying blood for it, even if these are not the way this 'god' is generally served.
Males and females
In Masechta Avodah Zara
It is obvious
If one transgresses
With witnesses and warning he gets stoned, by mistake he brings a Korban Chatos.
Everything in Judaism rests on this, as Chazal say כל המודה בעבודה זרה כאילו כפר בכל התורה כולה
This Mitzva is incumbent on non-Jews as well but there are details which are different for non-Jews.