Bhashya
एतमु एवाहमभ्यगासिषमित्यादि पूर्ववदेव ।अतो वागादीन्मुख्य च प्राण भेदगुणविशिष्टमुद्गीथ पश्यन् भूमान मनसा अभिगायतात् , पूर्ववदावर्तेयेत्यर्थ , बहवो वै मे मम पुत्राभविष्यन्तीत्येवमभिप्राय सन्निधये ।प्राणादित्यैकत्वोद्गीथदृष्टे एकपुत्रत्वफलदोषणापादितत्वात् रश्मिप्राणभेददृष्टे कर्त-व्यता चोद्यते अस्मिन्खण्ड बहुपुत्रफलत्वार्थम् ॥
In plain words
The text starting with 'This very prana I approached with praise' is interpreted as before. Therefore, recognizing speech and the other organs as distinct forms subordinate to the chief prana, one should mentally meditate on the infinite udgitha, repeating the practice so that many sons may be born. Since seeing prana and the sun as identical leads to the undesirable result of having only a single son, this section enjoins a meditation recognizing the distinction between the sun's rays and prana, specifically to secure the blessing of many offspring.
Close to the Sanskrit
The passage beginning with 'This one indeed I praised' is just like before. Hence, viewing speech and other organs along with the chief prana as possessing the quality of distinction, one should mentally sing toward the infinite udgitha, repeating as before, with the intention that 'many sons will be mine.' Because the vision of the identity of prana and the sun in the udgitha brings about the fault of the result of having a single son, the duty of meditation based on the distinction of rays and prana is enjoined in this section for the purpose of obtaining the fruit of many sons.