Shiva Purana
स कर्ता कारणं सेति तयोर्भेदो व्यवस्थितः ॥ एक एव शिवः साक्षाद्द्विधा ऽसौ समवस्थितः ॥ ३२ ॥
Their difference is specified in this that he is the maker and she is the cause. The single Śiva himself stands two-fold.
english translation
sa kartA kAraNaM seti tayorbhedo vyavasthitaH ॥ eka eva zivaH sAkSAddvidhA 'sau samavasthitaH ॥ 32 ॥
hk transliteration by Sanscript