why-do-hindus-believe-in-cremation-instead-of-burial ?
One of the reasons and explanations why Hindus believe cremation of the dead is also given in Brihadaranyaka Upanishad - Adhyaya 5 - Brahmana 12 - " Tapo Brahmanam".
It's said in the Upanishad that cremating a deceased by others is equal to excellent austerity or "Tapa" performed by the dead person.
It said that when people keep the dead in cremation fire, it's similar to Agni- Pravesha (entering into the fire) and is like performing excellent austerity by him. And the person who knows that wins the highest world.
एतद् वै परमम् तपस् यम् प्रेतम् अरण्यम् हरन्ति परम हैव लोकं जयति य एवं वेदैतद्वै परमं तपो यं प्रेतमरण्य हरन्ति यस् एवम् वेद एतद् वै परमम् तपस् यम् |प्रेतम् अरण्यम् हरन्ति परम हैव लोकं जयति परमम् ह एव लोकम् जयति य एवं वेदैतद्वै परमं तपो यं प्रेतमग्नावभ्यादधति यस् एवम् वेद एतद् वै परमम् तपस् यम् प्रेतम् अग्नौ अभ्यादधति परम हैव लोकं जयति || BU 5.11.1||
This is indeed excellent austerity that man after death is placed in fire. He knows as above wins an excellent world.
explanation of Shankara's commentary - The concept of cremation is a belief that as Agni makes all things pure by burning the impurities in substances, similarly Agni burns all the evil of a dead person when placed on fire i.e. when he is cremated.
And this removal of the evil of the dead by Agni is similar to performing excellent Tapas by the dead. And that helps him in achieving supreme world if he knows about this. And this is one of the reasons why Hindus perform cremation of the dead.
And here are the screenshots of Gita Press Hindi translation and explanation.
[![enter image description here][2]][2]