The Self and the self
ऋतं पिबन्तौ सुकृतस्य लोके
गुहां प्रविष्टौ परमे परार्धे ।
छायातपौ ब्रह्मविदो वदन्ति
पञ्चाग्नयो ये च त्रिणाचिकेताः ॥ १॥
ṛtaṃ pibantau sukṛtasya loke
guhāṃ praviṣṭau parame parārdhe .
chāyātapau brahmavido vadanti
pañcāgnayo ye ca triṇāciketāḥ .. 1..
Two there are who dwell within the body, in the intellect, the supreme akasa of the heart, enjoying the sure rewards of their own actions. The knowers of Brahman describe them as light and shade, as do those householders who have offered oblations in the Five Fires and also those who have thrice performed the Nachiketa sacrifice.
Swami Vivekananda Says —
In us are two — The God-soul and the man-soul. The sages know that the latter is but the shadow, that the former is the only real Sun.[Source]
…if any work is done, good or bad, it must produce as a result a good or bad effect; no power can stay it, once the cause is present. Therefore good action producing good Karma, and bad action, bad Karma, the soul will go on in eternal bondage without ever hoping for deliverance. Now Karma belongs only to the body or the mind, never to the Atman (Self); only it can cast a veil before the Atman.[Source]