Shiva Purana
एवं पूजयतोः शम्भुं राजद्विजकुमारयोः ॥ सुखेनैव व्यतीयाय तयोर्मासचतुष्टयम् ॥ ७०॥
Thus four months elapsed as the two boys continued their worship of Śiva.
english translation
evaM pUjayatoH zambhuM rAjadvijakumArayoH ॥ sukhenaiva vyatIyAya tayormAsacatuSTayam ॥ 70॥
hk transliteration by Sanscript