Shiva Purana
यथा पूर्वोक्तमार्गेण शिवत्वं येन जायते ॥ नाशिवः शिवमभ्यस्येन्नाशिवः शिवमर्चयेत् ॥ ४२ ॥
By the process described above, one can become Lord Śiva. One who is not auspicious should not practice Lord Śiva and one who is not auspicious should not worship Lord Śiva.
english translation
yathA pUrvoktamArgeNa zivatvaM yena jAyate ॥ nAzivaH zivamabhyasyennAzivaH zivamarcayet ॥ 42 ॥
hk transliteration by Sanscript