I agree with the above, but perhaps you are asking about something that came before the murder. While Macbeth is about to do the deed, Lady Macbeth is alone and says (again Act 2, Scene 2):
That which hath made them drunk hath
made me bold;
What hath quench'd them hath given me fire. Hark! Peace!
It was the owl that shriek'd, the fatal bellman,
Which gives the stern'st good-night. He is about it:
The doors are open, and the surfeited grooms
Do mock their charge with snores: I have drugg'd their possets,
That death and nature do contend about them,
Whether they live or die.
What she says she has done is this: she has put some kind of powerful sleeping potion into their spiced drinks (possets), so that they are not only asleep but in a kind of drugged stupor.
Here's her full plan, that was hatched back in Act 1 , Scene 7:
When Duncan is asleep—
Whereto the rather shall his day's hard journey
Soundly invite him—his two chamberlains
Will I with wine and wassail so convince,
That memory, the warder of the brain,
Shall be a fume and the receipt of reason
A limbec only. When in swinish sleep
Their drenched natures lie as in a death,
What cannot you and I perform upon
The unguarded Duncan?
In Act II Sc.2 Macbeth meets Lady Macbeth after he has murdered King Duncan. He looks at his blood stained hands and is deeply perturbed and his mind is weighed with guilt at the thought of the heinous crime he has committed. His wife tries to console him saying that he should not consider what he has done too seriously,and asks him to wash his hands. Just then she notices that Macbeth is still carrying with him the murder weapons - the daggers- with him. She asks him to go and leave the daggers with the grooms and smear them with Duncan's blood so that it will seem as though they have murdered the king. Macbeth refuses saying that he is terrified at the thought of what he has done and that he will not visit the scene of crime.
At once Lady Macbeth asks him to give her the daggers saying that she will go and smear the grooms with Duncan's blood and leave the daggers beside them to create the false impression that they have murdered Duncan:
Who was it that thus cried? Why, worthy thane,
You do unbend your noble strength, to think
So brainsickly of things. Go get some water,
And wash this filthy witness from your hand.
Why did you bring these daggers from the place?
They must lie there: go carry them; and smear
The sleepy grooms with blood.