Here Shastra means Vedas. Vidhi stands for injunction. He who abandons My injunction called Vedas and acts under the influence of desire, viz., takes the path according to his own wishes, does not attain perfection, He does not reach any Siddhi in the next world, nor does he find the slightest happiness in this world, let alone the attainment of the supreme state. It is not possible for him to do so. Such is the meaning.