“Taistanyadhani puyante tapodaanjapadibhi
Nadharmajam taddhrudaym tadpishandhrisewaya”( Part 6-2-27)
“Vedic karm such as charity, fire sacrifice, penance, fasting etc does destroy sin, but it cannot purify the heart.” You may ask that when sins are destroyed, will not the heart be automatically purified? But it is not so. Let us say that a person has committed the sin of killing a cow. If he performs the atonement for it according to Vedic karm, his sin will be destroyed, but his sinful mentality will remain. Thus, he will commit sin again. Now, he may repeatedly commit sin, and then do the atonement for it, but the heart will never be purified in this way.
Secondly, the sin is committed in a short time, but the performance of the atonement takes an exceedingly long time. Besides, even if we suppose that all the present sins have been destroyed through actions of atonement, there will still be innumerable accumulated sins from endless past lifetimes. These will never be destroyed even by repeated atonement, because the accumulated sins of endless past lifetimes are infinite. Thus, to purify the heart, devotion has to be performed. Adi Shankaracharya has said:
“Shudhayati hi naantratma krishnapadambhoj Bhaktiyuke”
“Without devotion to the Supreme Lord Shree Krishn, the heart can never be cleansed.” And when the heart is not cleansed, there is no guarantee that external repentance for sins will prevent the person from committing sins in the future. The conclusion is that the mere performance of karm without devotion, is not only incapable of giving liberation, it does not even result in the purification of the heart.