Shiva Purana
दिनानि पंच चारभ्य पंचविंशद्दिनावधि ॥ वामाचारगतौ नादः प्रमाणं कथितं तव ॥ ४१॥
Beginning with the fifth and ending with the twenty-fifth are the calculations of sound according to the left-hand practices.
english translation
dinAni paMca cArabhya paMcaviMzaddinAvadhi ॥ vAmAcAragatau nAdaH pramANaM kathitaM tava ॥ 41॥
hk transliteration by Sanscript