अथैनं मात्रे प्रदाय स्तनं प्रयच्छति यस्ते स्तनः शशयो यो मयोभूर्यो रत्नधा वसुविद्यः सुदत्रः ।येन विश्वा पुष्यसि वार्याणि सरस्वति तमिह धातवे करिति ॥६,४.२७ ॥
In plain words
Then, giving him to his mother, he offers the breast, saying: "That breast of thine which is unfailing, which is refreshing, the giver of treasure and the finder of wealth, the bountiful one, by which thou nourishest all things desirable — bring it here, Sarasvatī, for him to suck."
The commentators
Bṛhadāraṇyakopaniṣadbhāṣyam· bhāṣya
अथैनं मात्रे प्रदाय स्वाङ्कस्थम्, स्तनं प्रयच्छति 'यस्ते स्तनः' इत्यादिमन्त्रेण ॥
In plain words
He hands the child to his mother, who settles him in her lap and offers her breast, speaking the mantra that begins 'that breast of yours...'.
Close to the Sanskrit
Then, having given him over to the mother, [the child now] resting in her own lap, she gives [him] the breast, by the mantra beginning 'that breast of yours' [and so on].