Srila Rupa Gosvami writes in his Bhakti-rasamrta-sindhu (1.2.101): sruti-smri-puranadi-
pancaratra-vidhim vina
aikantiki harer bhaktir
utpptayaiva kalpate “Devotional service of the Lord that ignores the authorized Vedic literatures like the Upanisads, Puranas and Narada-pancaratra is simply an unnecessary disturbance in society.”