Shemot (Exodus) 20:5
Lo-tishtachaveh lahem velo ta'ovdem ki anochi YHVH Eloheycha El kana poked avon avot al-banim al-shileshim ve'al-ribe'im leson'ay.
You shall not bow down to them nor serve them. For I, YHVH your Elohim, am a jealous El, visiting the iniquity of the fathers on the children to the third and fourth generations of those who hate Me.

This mitzvah comes from the Aseret-Hadibrot, Ten Sayings, often known as the Ten Commandments. It is part of the second saying. It specifically prohibits bowing down before a graven image. In Judiasm, there are four acts of service that are associated with "bowing" down before YHVH: bowing down, offering sacrifices, burning incense, and libation offerings.

Divrei HaYamim B (2 Chronicles) 25:14
Now it happened, after that Amatzyah was come from the slaughter of the Edom, that he brought the elohim of the children of Se'ir, and set them up to be his elohim, and bowed down himself before them, and burned incense to them.

Here we see the association between burning incense and bowing down.

Even if any of these four practices are not the normal way of worshipping an idol, it is still prohibited.

The reason given for this mitzvah is that He is YHVH, our Elohim and He is a jealous El. The Hebrew word for jealous is "kana." It is used exclusively with relationship with YHVH. He demands exclusive worship (Rabbi Hirsch).

Deuteronomy 32:21 They have moved me to jealousy with that which is not Elohim; They have provoked me to anger with their vanities: I will move them to jealousy with those who are not a people; I will provoke them to anger with a foolish nation.

It is the same way that someone will be jealous if their spouse cheats on themFor jealousy arouses the fury of the husband. He won't spare in the day of vengeance. (Mishlei/Proverbs 6:34)

The Sifrei teaches that those who violate this mitzvah has sacrificed to demons.

Devarim (Deuteronomy 32:16-17)
They moved him to jealousy with strange elohim; With abominations provoked they him to anger. They sacrificed to demons, which were not Elohim, To elohim that they didn't know, To new ones that came up of late, which your fathers didn't dread.

1 Corinthians 10:16-22
The "cup of blessing" over which we make the b'rakhah-isn't it a sharing in the blood sacrificial death of the Messiah? The matzah we break, isn't it a sharing in the body of the Messiah? Because there is one bread, we who are many constitute one body, since we all partake of the one bread. Look at physical Israel: don't those who eat the sacrifices participate in the altar? So, what am I saying? That food sacrificed to idols has any significance in itself? or that an idol has significance in itself'? No, what I am saying is that the things which pagans sacrifice, they sacrifice not to God but to demons; and I don't want you to become sharers of the demons! You can't drink both a cup of the Lord and a cup of demons, you can't partake in both a meal of the Lord and a meal of demons. Or are we trying to make the Lord jealous? We aren't stronger than he is, are we?

Mattityahu (Matthew) 4:8-10
Again, the devil took him to an exceedingly high mountain, and showed him all the kingdoms of the world, and their glory. He said to him, "I will give you all of these things, if you will fall down and worship me. Then Yeshua said to him, "Get behind me, Hasatan! For it is written, ‘You shall worship YHVH your Elohim, and him only shall you serve."