Bhagavad Gita Chapter 17.13
vidhi-hīnam asṛṣṭānnaḿ
mantra-hīnam adakṣiṇam
śraddhā-virahitaḿ yajñaḿ
tāmasaḿ paricakṣate
Translation
Any sacrifice performed without regard for the directions of scripture, without distribution of prasadam [spiritual food], without chanting of Vedic hymns and remunerations to the priests, and without faith is considered to be in the mode of ignorance.