Shiva Purana
सङ्ख्या विशक्यते कर्तुं सुप्राज्ञैर्बहुजन्मभिः ॥ शिवावताराणां नैव सत्यं जानीहि मद्वचः ॥ ७॥
It is possible to count them in many births by the wise Know that my words are not true of the incarnations of Lord Śiva.
english translation
saGkhyA vizakyate kartuM suprAjJairbahujanmabhiH ॥ zivAvatArANAM naiva satyaM jAnIhi madvacaH ॥ 7॥
hk transliteration by Sanscript