You will need:
Creek stones
An earthen bowl
Natural water

The 'Wyrd' sisters are similar to the Moirai in Greek mythology. The first sister represents the past; the second sister symbolizes the present; and the third sister being the future.

The purpose of this ritual is to deflect negativity. Fill the bowl nearly full of creek stones, then fill the bowl with water, preferably from any natural form of water, or filtered water. The chant used here is:

''Bowl of reflection
Stones of protection
May the reason of my harm
Feel the power of this charm.
Sisters three come work for me
Bowl detect
Stones deflect
And water reflect
Peace and harmony now come to me.
As I will, so mote it be.''

Change the water once a week and renew the chant. Throw the old water on your doorstep. The Sisters of the Wyrd are incorporated here. The bowl stands for the first sister, she of the past; the stones for the second sister- the present; the third action, that of reflection, is the sister of the future, the third sister.

Source: http://www.spellsofmagic.com