Skandapurana 5.71.43

5.71.43

tasyāṃ śaktau naro yaśca kuryātpṛṣṭhinigharṣaṇam..
pūjayitvā tu puṣpādyaiḥ samyakchraddhāsamanvitaḥ ..
sa na syādrogasaṃyukto yāvatsaṃvatsaraṃ dvijāḥ .. 43 ..

And whatever man should rub his back against that spear, / having worshipped it with flowers and the like, endowed with proper faith, / he will not be afflicted with illness for a whole year, O twice-born.