It was not Shiva but Vishnu, who cut the body of Sati into peices.
Enraged at the insult and death of his spouse and immersed in grief, Shiva picked up the remains of Sati's body and performed the Tandava, the celestial dance of destruction, across all creation. Frightened, the other Gods requested Vishnu to intervene to stop this destruction. As a recourse, Vishnu used the Sudarshana Chakra on Sati's corpse dismembering the body of Sati into 108 parts, from which 51 fell on earth and others on other planets in the universe which became Shakti Peethas, temple to a form of the Goddess.
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