While this reference to blood, evil and guilt does not actually appear in the text of Macbeth, one can apply it to the play. Given that the image of blood is very important in the play (the "damned spot" on Lady Macbeth's hand, the bloodied apparition), the statement in question proves to be very true for many of the characters in the play.
Essentially what the statement is saying, in the first part ("blood is proof of evil"), can be defined in two different ways. First, all of mankind has blood which runs through their bodies; therefore, all of mankind is capable of evil (proven when Macbeth makes the choice to murder Duncan in order to gain the throne--instead of waiting for fate to allow it). Second, the statement refers to the fact that if blood is seen (as it is in the murder of Duncan) then evil caused it.
The second part of the statement holds truthful in Macbeth as well. Essentially, the blood which runs through one's body can symbolize the guilt they feel for their evil behavior. Here again, the reference to the "damned spot" is important. Without the stain upon her hand, Lady Macbeth may not have been driven to madness. Given that she could not wash away the guilt by washing off the blood, her guilt is just as much a part of her as her blood. Even Macbeth realizes it is not as easy as washing off his hands in order to remove his guilt.
What hands are here? Ha, they pluck out mine eyes!
Will all great Neptune's ocean wash this blood
Clean from my hand?