विधिहीनमसृष्टान्नं मन्त्रहीनमदक्षिणम् ।
श्रद्धाविरहितं यज्ञं तामसं परिचक्षते ॥ १७.१३ ॥

vidhi-hīnam-asṛṣṭānnaṁ mantra-hīnam-adakṣiṇam |
śraddhā-virahitaṁ yajñaṁ tāmasaṁ paricakṣate || 17.13 ||

Yajñas or sacrifices, however holy they may be, if done disregarding scriptural pronouncements, giving no importance to mantras, divine recitations, forsaking śraddhā, refusing to give the necessary consideration and rewards to Vedic scholars and priests, are undoubtedly tāmasika and only adverse outcome will follow such performance.