BṚHADĀRAṆYAKA UPANISHAD · 6.4.15

अथ य इच्छेत् -- पुत्रो मे कपिलः पिङ्गलो जायेत द्वौ वेदाव् अनुब्रुवीत सर्वम् आयुर् इयाद् इति दध्योदनं पाचयित्वा सर्पिष्मन्तम् अश्नीयाताम् ।
ईश्वरौ जनयितवै ॥

atha ya icchet -- putro me kapilaḥ piṅgalo jāyeta dvau vedāv anubruvīta sarvam āyur iyād iti dadhyodanaṃ pācayitvā sarpiṣmantam aśnīyātām ।
īśvarau janayitavai ॥

Now, in case one wishes, 'That a tawny son with reddish-brown eyes be born to me! that he be able to recite two Vedas! that he attain the full length of life!'--they two should have rice cooked with sour milk and should eat it prepared with ghee. They two are likely to beget [him].

Robert Ernest Hume · The Thirteen Principal Upanishads (1921), Bṛhadāraṇyaka VI.4