Īśāvāsyopaniṣat 03
असुर्या नाम ते लोका अन्धेन तमसाऽवृताः। तान् ते प्रेत्याभिगच्छन्ति ये के चात्महनो जनाः ॥३॥
asuryā nāma te lokā andhena tamasā'vr̥tāḥ। tān te pretyābhigacchanti ye ke cātmahano janāḥ ॥3॥
Those worlds named 'Asura', i.e. demoniacal, are enveloped in the darkness of ignorance. Those killers of the self (i.e. those who do not take authentic honest actions), attain them after death.
Īśā.Bhāshya 03
'Asurya' - having the nature to delight in contrary to good. Also, it is opposite of 'sura', i.e. gods. Thus it means those who turn away from lord Hari.
Those who delight in contrary to good are demons. Having such a nature is 'asuryā', i.e. demoniacal.
"Indeed, they are not happy. They worship the non existent, promote nihilism, and are killers of the self."
- because it is stated thus in the testimonial (Bhagavata Purana).
"The demons acquire them as they are the sole cause of the intense suffering. Those worlds are called 'Asurya', i.e. opposed to 'sura' i.e. gods, as those who turn away from lord Hari attain them."
- thus stated in the Vāmana Purāna.
By stating 'ye ke', i.e. 'those who', the rule is conveyed (i.e. those opposed to the lord mandatorily attain darkness).
"By rule, all, turned away from Hari, attain darkness"
- there are such testimonials as well.
