This passage deals with the king Duncan's murder by Macbeth, who is completely
obsessed by his sense of guilt, while Lady Macbeth is much more pityless and self confident. The two of them, indeed, react to what has been done in different ways: Macbeth is paranoid and is afraid of someone discovering it, while Lady Macbeth is completely numb. Indeed she mocks him and rebukes him, she brainwashes him and blackmails him, this shows that their relationship is unbalanced, and will be until the end.
Macbeth is really afraid of going in Duncan's room to bring the daggers back, so Lady Macbeth does it, calling him “infirm of purpose”; and whe she comes back she makes fun of him saying “my hands are of your colour, but i shame to wear a heart so white”, she mocks him for being a coward, indeed white doesn't reffer to purity but to cowardice.
In this passage there are many rhetorical devices, for example Macbeth personifies Sleep, which is innocent because sleeping people are defenseless and harmless, he emphasises this because he killed Duncan while he was asleep. Furthermore, Shakespeare used an hyperbole when Macbeth claims that not even all of Neptune's ocean will be able to clean his hands from blood. Lady Macbeth is not concerned at all by these feelings, indeed she remarks him that if he keeps thinking about it, he will become mad; indeed at the end she will become mad and start sleepwalking trying to wash out the blood of her hands. This is connected with the idea of sleep conveyed by Macbeth. That's why their relationship wll be unbalanced until the end, because their personalities will reverse, she will become as he was at the beginning and viceversa.