Verse 1.3.12

आत्मानमन्तत उपसृत्य स्तुवीत कामं ध्यायन्नप्रमत्तोऽभ्याशो ह यदस्मै स कामः समृध्येत यत्कामः स्तुवीतेति यत्कामः स्तुवीतेति ॥ १.३.१२ ॥
॥ इति तृतीयः खण्डः ॥

ātmānamantata upasṛtya stuvīta kāmaṃ dhyāyannapramatto'bhyāśo ha yadasmai sa kāmaḥ samṛdhyeta yatkāmaḥ stuvīteti yatkāmaḥ stuvīteti || 1.3.12 ||
|| iti tṛtīyaḥ khaṇḍaḥ ||

12. Finally, as a person ends his prayer, he should ask for whatever he desires, making sure, however, that his pronunciation is correct. He should also think of himself [including his name, lineage, and caste]. Then whatever desire he has while praying is promptly and surely fulfilled.

Word-for-word explanation:

Antataḥ, as one ends one’s prayer; kāmam dhyāyan apramattaḥ, one should think of whatever one desires, making sure that the pronunciation of words is correct; ātmānam, oneself; upasṛtya, thinking of [one’s name, lineage, and caste]; stuvīta, praise; yat kāmaḥ, whatever desire one has; stuvīta, while praying; kāmaḥ, that desire; abhyāsaḥ, promptly; ha, surely; asmai, to the person concerned; samṛdhyeta, prosperity goes. [The repetition is for emphasis.] Iti tṛtīyaḥ khaṇḍaḥ, here ends the third section.

Commentary:

Here the udgātā (the singer) is told how he should pray. He should first repeat the Sāma songs, and then he should pray for whatever he desires. His prayer should be correct in every detail. And while praying, he should mention his own name, his lineage, and his caste. If these conditions are fulfilled, his prayer will be promptly granted. That this will happen is indicated by the repetition of the statement.