In his Brahma Sutra Bhasya 1.3.28, Adi Shankaracharya gives a long commentary while proving about the eternity of Vedas.
He quotes about various scriptures there like:
Thus Scripture declares in different places that the word precedes the creation.--Smrti also delivers itself as follows, 'In the beginning a divine voice, eternal, without beginning or end, formed of the Vedas was uttered by Svayambhû, from which all activities proceeded. 'By the 'uttering' of the voice we have here to understand the starting of the oral tradition (of the Veda), because of a voice without beginning or end 'uttering' in any other sense cannot be predicated.--Again, we read, 'In the beginning Mahesvara shaped from the words of the Veda the names and forms of all beings and the procedure of all actions.' And again, 'The several names, actions, and conditions of all things he shaped in the beginning from the words of the Veda' (Manu I, 21). Moreover, we all know from observation that any one when setting about some thing which he wishes to accomplish first remembers the word denoting the thing, and after that sets to work. We therefore conclude that before the creation the Vedic words became manifest in the mind of Pragâpati the creator, and that after that he created the things corresponding to those words.
From where is the quote in bold taken? The Sanskrit of it is as:
नाम रुपं च भूतानां कर्मणां च प्रवर्तनम् ।
वेदशब्देभ्य एवादौ निर्ममे स महेश्वर ।।
nāma rupaṃ ca bhūtānāṃ karmaṇāṃ ca pravartanam ।
vedaśabdebhya evādau nirmame sa maheśvara ।।