The witches never told him to kill King Duncan. The witches never told Macbeth to murder Banquo. All the witches told Macbeth was that "All hail Thane of Glamis, All hail Thane of Cawdor." Which meant Long live king of Glamis and long live the king of Cawdor. Lady Macbeth and her evil and selfish self came up with the plan to murder king Duncan so that macbeth can also become the king of Scotland. And at the end of the play in act four scene one the witches told macbeth about the prophecies they had which were the bloody child, a crowned king with a tree in the hand, 8 crowned kings walking together, and ?.It was up to macbeth if he wanted to believe them or not. Macbeth fell because of both his fate and free will. I believe its free will because all was going well, he was named and honored with the title of king of Glamis and king of Cawdor. If he had a little more patience a couple of more years he would have been king of Scotland as well. The way Lady Macbeth manipulated Macbeth made him murder Duncan, this one mistake ruined the whole thing. All was well but the words Lady Macbeth used which were "coward" and other nasty things and said how if macbeth told lady Macbeth to take a child and bash the brains out of the child she would do that for him and he could not do anything for her. Macbeth stated that King Duncan was a noble and a very good man how can he hurt him and backstab him like this.