Vishvamitrasmriti 8.36

8.36

madhyakāle tu madhyāhne dakṣiṇāyanage ravau
vaiśvadevaṃ prakurvīta madhyakālācca pūrvataḥ

In the middle period at midday when the sun has gone to the southern course, / one should perform the universal offering rite before the middle period;