Bhashya
तम् एतम् उ एव अहम् अभ्यगासिषम् आभिमुख्येन गीतवानस्मि, आदित्यरश्म्यभेद कृत्वा ध्यान कृतवानस्मी- त्यर्थ ।तेन तस्मात्कारणात् मम त्वमेकोऽसि पुत्र इति ह कौषीतकि कुषीतकस्यापत्य कौषीतकि पुत्रमुवाच उक्तवान् ।अत रश्मीनादित्य च भेदेन त्व पर्यावर्तयात् पर्यावर्तये त्यर्थ , त्वयोगात् ।एव बहवो वै ते तव पुत्रा भविष्य-न्ती त्यधिदैवतम् ॥
In plain words
That is what I approached in song with a direct and focused mind, meditating on the identity between myself and the sunbeams—this is the meaning. Therefore, for that reason, Kauṣītaki, the descendant of Kuṣītaka, said to his son, 'You are my only son.' Hence you should regard the sun and its rays as distinct, because of your special connection. Thus indeed, many sons of yours will be born, viewed from the standpoint of the cosmic deities.
Close to the Sanskrit
That very this I approached in song, having performed meditation making non-difference with the sunbeams, meaning. Therefore, for that reason, 'you are my only son,' thus Kauṣītaki, the offspring of Kuṣītaka, spoke to his son. Hence you should turn around the rays and the sun with difference, meaning, because of your association. Indeed thus many sons of yours will be, regarding the deities.