tad asma-saram hrdayam batedam
yad grhyamanair hari-namadheyaih
na vikriyetatha yada vikaro
netre jalam gatra-ruhesu harsah
tat—that; asma-saram—as hard as iron; hrdayam—heart; bata—O; idam—this; yat—which; grhyamanaih—in spite of taking the chanting; hari-namadheyaih—meditating on the holy name of the Lord; na—does not; vikriyeta—change; atha—thus; yada—when; vikarah—transformation; netre—in the eyes; jalam—tears; gatra-ruhesu—in the pores of the body; harsah—ecstasy.
"If one's heart does not change, tears do not flow from his eyes, his body does not shiver, and his bodily hairs do not stand on end as he chants the Hare Krsna maha-mantra, it should be understood that his heart is as hard as iron. This is due to his offenses at the lotus feet of the Lord's holy name."
Srila Bhaktisiddhanta Sarasvati Thakura, commenting on this verse, which is a quotation from Srimad-Bhagavatam (2.3.24), remarks that sometimes a maha-bhagavata, or very advanced devotee, does not manifest such transcendental symptoms as tears in the eyes, and sometimes a kanistha-adhikari, a neophyte devotee, displays them artificially. This does not mean, however, that the neophyte is more advanced than the maha-bhagavata devotee. The test of the real change of heart that takes place when one chants the Hare Krsna maha-mantra is that one becomes detached from material enjoyment. This is the real change. Bhaktir paresanubhavo viraktir anyatra ca (Bhag. 11.2.42). If one is actually advancing in spiritual life, he must become very much detached from material enjoyment. If it is sometimes found that a kanistha-adhikari (neophyte devotee) shows artificial tears in his eyes while chanting the Hare Krsna mantra but is still completely attached to material things, his heart has not really changed. The change must be manifested in terms of one's real activities.
Link to this page: https://prabhupadabooks.com/cc/adi/8/25