जातेऽग्निमुपसमाधायाङ्क आधाय कंसे पृषदाज्यं संनीय पृषदाज्यस्योपघातं जुहोति अस्मिन्सहस्रं पुष्यासमेधमानः स्वे गृहे ।अस्योपसन्द्यां मा छैत्सीत्प्रजया च पशुभिश्च स्वाहा ।मयि प्राणांस्त्वयि मनसा जुहोमि स्वाहा ।यत्कर्मणात्यरीरिचं यद्वा न्यूनमिहाकरम् ।अग्निष्टत्स्विष्टकृद्विद्वान् स्विष्टं सुहुतं करोतु नः स्वाहेति ॥६,४.२४ ॥
In plain words
When the child is born, he lays the fire, takes him on his lap, and having mixed curd and butter together in a metal cup, he offers of that mixture, saying: "In this child may I nourish a thousand and prosper in my own house. May fortune never be cut off from his line, with offspring and with cattle — svāhā. The breaths that are in me I offer up in thee with my mind — svāhā. Whatever in the rite I have done too much, or whatever I have here left undone, may Agni, the knowing one, the maker of right offering, make it rightly offered and well offered for us — svāhā."
The commentators
Bṛhadāraṇyakopaniṣadbhāṣyam· bhāṣya
अथ जातकर्म । जातेऽग्निमुपसमाधाय अङ्के आधाय पुत्रम्, कंसे पृषदाज्यं संनीय संयोज्य दधिघृते, पृषदाज्यस्य उपघातं जुहोति 'अस्मिन्सहस्रम्' इत्याद्यावापस्थाने ॥
In plain words
Now comes the birth-rite. Once the child is born, the father lights the fire, sets the boy on his lap, mixes curds and ghee together in a bowl, and offers this pṛṣadājya into the fire, saying 'in this one, a thousand' and the rest of that formula, as he pours the offering.
Close to the Sanskrit
Now, the birth-rite (jātakarma). When [the child] is born, having kindled the fire, having placed the son on [his] lap, having brought together and blended curds and ghee into pṛṣadājya in a vessel, he offers the striking-oblation of the pṛṣadājya, [with] 'in this one, a thousand' and so on, at the occasion of pouring.