"We will proceed no further in this business: He hath honored me of late; and I have bought golden opinions from all sorts of people, which would be worn now in their newest gloss, not cast aside so soon" (1.7.33-37).
Macbeth's Shift
"I am in blood stepp'd in so far that, should I wade no more, returning were as tedious as go o'er" (3.4.160-162).
The 'New' Macbeth
After Macbeth is contemplating the murder of Duncan he then comes to the conclusion not to kill him. Immediately, he tells Lady Macbeth the plan is off; The king has honored him, he's well liked by the people and shouldn't risk anything being taken away.
Macbeth's turning point in the play is when he suspects Banquo and hires the murderers to kill him. Going after his friend shows how evil he's become and will stop at nothing to keep his throne. Especially after he tells Lady Macbeth he's stepped so far into evil that it'll be harder for him to go back to be good rather than to just keep up the killing.