Bhakti-rasāmṛta-sindhu .2.95
Blended reading (Sanskrit + English inline)
Now, the total regulative principles come to an aggregate of sixty-four items. As we have mentioned, the first are the primary ten regulative principles. Then come the secondary ten regulative principles, and added to these are forty-four other activities. So all together there are sixty-four items for discharging the regulative practice of devotional service. Out of these sixty-four items, five items—namely worshiping the Deity, hearing Śrīmad-Bhāgavatam, associating among the devotees, saṅkīrtana, and living in Mathurā—are very important. The sixty-four items of devotional service should include all of our activities of body, mind and speech. As stated in the beginning, the regulative principle of devotional service enjoins that all of our senses must be employed in the service of the Lord. Exactly how they can be thus employed is described in the above sixty-four items. Now, Śrīla Rūpa Gosvāmī will give evidence from different scriptures supporting the authenticity of many of these points.
My note
Source: vedabase.io