Paraskaragrihyasutra 1.16.4

1.16.4

anāmikayā suvarṇāntarhitayā madhughṛte prājayati ghṛtaṃ vā bhūstvayi dadhāmi bhuvastvayi dadhāmi svastvayi dadhāmi bhūrbhuvaḥ svaḥ sarvaṃ tvayi dadhāmīti \4\

(The medhâganana is performed in the following way:) With his fourth finger and with (an instrument of) gold he gives (to the child) honey and ghee, or ghee (alone), to eat with (the formulas), 'Bhûh I put into thee; bhuvah I put into thee; svah I put into thee. Bhûr bhuvah svah everything I put into thee.'