Bhagwad Gita
Chapter 17, Verse 13
विधिहीनमसृष्टान्नं मन्त्रहीनमदक्षिणम्।श्रद्धाविरहितं यज्ञं तामसं परिचक्षते।।17.13।।
And that sacrifice performed in defiance of scriptural injunctions, in which no spiritual food is distributed, no hymns are chanted and no remunerations are made to the priests, and which is faithless—that sacrifice is of the nature of ignorance.