17.13

विधिहीनमसृष्टान्नं मन्त्रहीनमदक्षिणम् ।
श्रद्धाविरहितं यज्ञं तामसं परिचक्षते ॥१३॥

vidhi-hīnam asṛṣṭānnaḿ
mantra-hīnam adakṣiṇam
śraddhā-virahitaḿ yajñaḿ
tāmasaḿ paricakṣate

vidhi- hīnam — without scriptural direction; asṛṣṭa- annam — without distribution of prasādam; mantra- hīnam — with no chanting of the Vedic hymns; adakṣiṇam — with no remunerations to the priests; śraddhā — faith; virahitam — without; yajñam — sacrifice; tāmasam — in the mode of ignorance; paricakṣate — is to be considered.

Text

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.

Purport

Faith in the mode of darkness or ignorance is actually faithlessness. Sometimes people worship some demigod just to make money and then spend the money for recreation, ignoring the scriptural injunctions. Such ceremonial shows of religiosity are not accepted as genuine. They are all in the mode of darkness; they produce a demoniac mentality and do not benefit human society.

Bhagavad Gita As It Is.

Chapter 17: The Divisions of Faith. Text 13

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.