It is the practice of Vaiṣṇavas while taking prasāda to chant the holy name of Lord Hari at intervals and also sing various songs, such as śarīra avidyā-jāla. Those who are honoring prasāda, accepting the remnants of food offered to the Deity, must always remember that prasāda is not ordinary food. Prasāda is transcendental. We are therefore reminded:
viśvāso naiva jāyate
Those who are not pious cannot understand the value of mahā-prasāda or the holy name of the Lord. Both prasāda and the Lord’s name are on the Brahman platform, or spiritual platform. One should never consider prasāda to be like ordinary hotel cooking. Nor should one touch any kind of food not offered to the Deity. Every Vaiṣṇava strictly follows this principle and does not accept any food that is not prasāda. One should take prasāda with great faith and should chant the holy name of the Lord and worship the Deity in the temple, always remembering that the Deity, mahā-prasāda and the holy name do not belong to the mundane platform. By worshiping the Deity, eating prasāda and chanting the Hare Kṛṣṇa mahā-mantra, one can always remain on the spiritual platform (brahma-bhūyāya kalpate).
Ref >> Srila Prabhupada Vani.