By Srila Bhaktivinoda Thakur
Six qualities that enhance Bhakti
Sanga-tyaga
Even if they are materialists, this type of engagement is not considered association. But if they are pure devotees, then such activities are performed out of love. When acts are performed out of love, then it is association. Therefore giving charity to pure Vaishnavas and accepting items or wealth from them becomes sat-sanga. Giving charity to a materialist or accepting charity from one, if done out of love, becomes asat-sanga.
When a materialist approaches you, whatever is required to be done should be done only out of duty. One should not speak confidentially with a materialist. Generally there is some love involved in confidential speaking, therefore it is association. While meeting a materialistic friend, one should speak only what is extremely necessary. At that time it is better not to exhibit heartfelt love. But if that friend is a proper Vaisnava, then one should accept his association by speaking to him with love. This type of behavior with relatives and friends creates no hostility. There is no association in ordinary talk.
One should behave with ordinary people as one externally behaves with a stranger while buying something in the market. The same dealings with a pure devotee of the Lord should be done out of love. If one is obliged to feed hungry people, needy people, and teachers, he should do so as a host dutifully cares for his guest, there is no need to exhibit love. Care for them, but not out of love. One should feed pure Vaishnavas with love, and when required accept the remnants given by them with love. If one can behave in this way while giving in charity, accepting charity, speaking confidentially, hearing confidentially, feeding, and accepting food with one's wife, children, servants, maidservants, strangers, and whoever else one meets, there will no unholy association, only good association. There is no hope of achieving devotion to Krsna until one gives up unholy association in this way.
A surrendered Vaisnava should accept whatever alms he receives by madhukari, or begging, at the house of a honest householder with the above mentioned consideration. He should always remember the difference between gross begging and madhukari. A grhastha Vaishnava should accept prashada-grains and drinks-in the house of another grhastha who has pure character. One should always be cautious about taking prasahda in the house of a nondevotee and one with bad character. There is no need to speak further about this. Due to their pious activities, those who have developed faith in devotional service have a little intelligence by the mercy of Krsna. Due to that intelligence they can easily understand the essence of the acaryas' instructions. Therefore only a few words are needed to instruct them. Those who have no pious credits have no faith. Even if they are given volumes of instruction, they will not understand a thing. Therefore Srila Rupa Gosvami has given only a few words of instruction in Sri Upadesamrta.
Source paramatma-meditation-course