Skandapurana 16.133.10

16.133.10

āśvayukchuklapakṣe tu navamyāṃ tatra jāgṛyāt ..
pīṭhe pūjābaliṃ dattvā mantraṃ kāmaṃ japanniśi ..
saumyacittaḥ samāpnoti vāṃchitāṃ siddhimuttamām .. 7.1.133.10 ..

One should keep vigil there on the ninth day in the bright fortnight of Āśvina; / having offered worship and oblations at the seat, muttering the mantra at night at will, / with a serene mind, one attains the highest desired perfection. 10