Shiva Purana
त्रिरात्रमेकरात्रं वा क्रमाच्छिवपदं लभेत् । स्ववर्णानुगुणं लोके स्वाचारात्प्राप्नुते नरः ६१ ।
By observing three nights or one night (of dedicated worship) in the prescribed manner, one can attain Shiva's supreme abode. According to their own caste and conduct, a person achieves what they deserve in this world.
english translation
trirAtramekarAtraM vA kramAcchivapadaM labhet । svavarNAnuguNaM loke svAcArAtprApnute naraH 61 ।
hk transliteration by Sanscript