I have used the following ‘incantation’ / ‘intention’ when clearing a space for many years, feel free to use or adapt to your belief system:
“I cleanse and clear all harmful and unwanted energies,
Releasing them back into the Universe
to be transformed for better use elsewhere.
And in its place, I fill this space
With the light, love and healing energy of (*your chosen deity here* eg Creator / Goddess / God)
As I will it, so mote it be”
Visualise pure, bright light filling the space or surrounding the person or object being cleansed, while whisps of dark smoke release and curl up and away into the sky.
Smoky Quartz is protective and dispels negative energy. Clear Quartz is a master healer, and boosts any purpose it is attuned to, as well as transmuting energy (bringing in light or transforming negative to positive). These two crystals work wonderfully in tandem during cleansing ceremonies.