I think 9/11 was a terrorist attack by a fundamentalist Islamic terrorist organization motivated by Bin Laden issuing fatāwā against America for stationing troops in Saudi Arabia and for supporting Israel. I think Bin Laden stating that he believed that it was a justified attack because of America's support for Israel points pretty solidly at the motivation behind the attacks:

"...it was a response to injustice, aimed at forcing America to stop its support for Israel..."

Also this from his video where he admits that he was behind the attacks and says that he was motivated by Israel bombing Lebanon

"...it entered my mind that we should punish the oppressor in kind and that we should destroy towers in America in order that they taste some of what we tasted..."

Interested in why you think oil had anything to do with 9/11. The destabilizing countries for oil stuff mostly came after 9/11. Middle Eastern hatred for America was mainly fueled by our support for Israel, and partially because Saudi Arabia had American military bases. Oil was not an interest to these terrorist groups until after Iraq.

Sources for those quotes:

http://news.bbc.co.uk/2/hi/middle_east/1729882.stm

https://www.aljazeera.com/news/2004/11/1/full-transcript-of-bin-ladins-speech