Sankaracarya's Vivekachudamani 460

कर्मणा निर्मितो देहः प्रारब्धं तस्य कल्प्यताम् ।

नानादेरात्मनो युक्तं नैवात्मा कर्मनिर्मितः ॥

karmaṇā nirmito dehaḥ prārabdhaṃ tasya kalpyatām |

nānāderātmano yuktaṃ naivātmā karmanirmitaḥ ||

(Sankaracarya's Vivekachudamani 460)

The body has been fashioned by prarabdha. So, regard prarabdha as belonging to the body. But it is not reasonable to attribute it to the Self, for the Self is beginningless and never created as a result of the past actions.

The human body is been given by the Lord according to our past Karma. This nature of Karma only applies to the body but the soul remains pure. It's a spark from the Supreme Lord. The soul has no beginning and end. Karmas are working for a soul as the past deed, but the soul itself doesn't get contaminated.