Skanda Purana 1.4.3.127

1.4.3.127

āṣāḍhasyāpi daśamī māghamāsasya saptamī..
śrāvaṇasyāṣṭamī kṛṣṇā tathāṣāḍhī ca pūrṇimā.. 5.127 ..

the tenth of Āṣāḍha, the seventh of the month of Māgha, / the dark eighth of Śrāvaṇa, and the full-moon day of Āṣāḍha;