This verse is a quotation from the Padma Purāṇa. There are many regulative principles in the śāstras and directions given by the spiritual master. These regulative principles should act as servants of the basic principle—that is, one should always remember Kṛṣṇa and never forget Him. This is possible when one chants the Hare Kṛṣṇa mantra. Therefore one must strictly chant the Hare Kṛṣṇa mahā-mantra twenty-four hours daily. One may have other duties to perform under the direction of the spiritual master, but he must first abide by the spiritual master’s order to chant a certain number of rounds. In our Kṛṣṇa consciousness movement, we have recommended that the neophyte chant at least sixteen rounds. This chanting of sixteen rounds is absolutely necessary if one wants to remember Kṛṣṇa and not forget Him. Of all the regulative principles, the spiritual master’s order to chant at least sixteen rounds is most essential.
One may sell books or enlist life members or render some other service, but these duties are not ordinary duties. These duties serve as an impetus for remembering Kṛṣṇa. When one goes with a saṅkīrtana party or sells books, he naturally remembers that he is going to sell Kṛṣṇa’s books. In this way, he is remembering Kṛṣṇa. When one goes to enlist a life member, he talks about Kṛṣṇa and thereby remembers Him. Smartavyaḥ satataṁ viṣṇur vismartavyo na jātucit. The conclusion is that one must act in such a way that he will always remember Kṛṣṇa, and one must refrain from doing things that make him forget Kṛṣṇa. These two principles form the basic background of Kṛṣṇa consciousness.