Shiva Purana
त्रिकं च साधनं मुक्तौ शिवेन मम भाषितम् । श्रवणादिं त्रिकं ब्रह्मन्कुरुष्वेति मुहुर्मुहुः 1-4-२० ।
Hence, O holy sage, as advised by Śiva these are the three means of salvation. Please practise them.” He repeatedly advised Vyāsa thus.
english translation
trikaM ca sAdhanaM muktau zivena mama bhASitam । zravaNAdiM trikaM brahmankuruSveti muhurmuhuH 1-4-20 ।
hk transliteration by Sanscript