5.14.7
The adoration of that (Gayatri): `O Gayatri, thou hast one foot, two feet, three feet, four feet. Thou art footless, for thou art not known. Worship to thy fourth bright foot above the skies.' If one (who knows this) hates some one and says, `May he not obtain this,' or `May this wish not be accomplished to him,' then that wish is not accomplished to him against whom he thus prays, or if he says, `May I obtain this.'