The Law Code of Yājñavalkya 1.10.42

1.10.42

ahno muhūrtā vikhyātā daśa pañca ca sarvadā |
tatrāṣṭamo muhūrto yaḥ sa kālaḥ kutapaḥ smṛtaḥ ||
madhyāhne sarvadā yasmān mandībhavati bhāskaraḥ |
tasmād anantaphaladas tatrārambho viśiṣyate ||
ūrdhvaṃ muhūrtāt kutapād yan muhūrtacatuṣṭayam |
muhūrtapañcakaṃ hy etat svadhābhavanam iṣyate ||
(MatsPu 22.84–85, 88)

"The muhūrtas of the day are universally known to be fifteen; / among them, the eighth muhūrta is the time remembered as kutapa. / Because the sun constantly grows dull at midday, / therefore an undertaking commenced then is distinguished as yielding endless fruit. / The four muhūrtas subsequent to the kutapa muhūrta— / indeed, these five muhūrtas are deemed the dwelling-place of svadhā."