Rishi: Yājñavalkya (traditional White Yajurveda transmission attribution; specific mantra-r̥ṣi as per anukramaṇī traditions)
Devata: Agni (explicit in the first member; subsequent members relate to Barhis and implements as ritual supports of the gods)
Chandas: Yajus (prose formula; not metrical in the strict sense)
Samhita Patha (Devanagari)कृष्णो॑ऽस्याखरे॒ष्ठोऽग्नये॑ त्वा॒ जुष्टं॒ प्रोक्षा॑मि॒ । वेदि॑रसि ब॒र्हिषे॑ त्वा॒ जुष्टां॒ प्रोक्षा॑मि । ब॒र्हिर॑सि स्रु॒ग्भ्यस्त्वा॒ जुष्टं॒ प्रोक्षा॑मि ॥
Transliterationkṛ́ṣṇo ’sy ākhareṣṭhó ’gnáye tvā júṣṭaṃ prókṣāmi | védir asi bárhiṣe tvā júṣṭāṃ prókṣāmi | bárhir asi srúgbhyas tvā júṣṭaṃ prókṣāmi ||
Translationতুমি কৃষ্ণবৰ্ণ, খোঁচনি/ঘষণিৰ বাবে সৰ্বাধিক উপযুক্ত। অগ্নিৰ বাবে—গ্ৰহণযোগ্য তোমাক মই ছিটাই দিছোঁ। তুমি বেদি; বৰ্হিষৰ বাবে—গ্ৰহণযোগ্য তোমাক মই ছিটাই দিছোঁ। তুমি বৰ্হিষ; স্ৰুগ (লাডল)সমূহৰ বাবে—গ্ৰহণযোগ্য তোমাক মই ছিটাই দিছোঁ।
Padapatha (Word Analysis)कृष्णः । असि । आखरेष्ठः । अग्नये । त्वा । जुष्टम् । प्रोक्षामि । वेदिः । असि । बर्हिषे । त्वा । जुष्टाम् । प्रोक्षामि । बर्हिः । असि । स्रुग्भ्यः । त्वा । जुष्टम् । प्रोक्षामि ।
Word by Wordआखरेष्ठःthe best/most excellent among the syllables (i.e., the foremost sound) जुष्टम्pleasing, acceptable बर्हिषेfor the barhis (sacrificial grass) जुष्टाम्pleasing, acceptable बर्हिःbarhis, sacrificial grass जुष्टम्pleasing, acceptable 
Entities MentionedB
Barhis (as sacred principle/seat of the gods) Viniyoga (Ritual Application)