SB 3.29.8

It is already stated in the Srimad-Bhagavatam, First Canto, Second Chapter, that the highest, glorious execution of religiosity is to attain the platform of devotional service without any motive and cause. So real pure devotional service is executed without any motive. The devotee must not have any kind of motive. That is pure devotional service. The only motive should be that he wants to please the Supreme Personality of Godhead. That is not actually motive.

That is the real pure condition of the living entity. And in the conditioned stage, when one is engaged in devotional service in full surrender, he should follow the instruction of the bona fide representative of the spiritual master. The spiritual master is the manifested representation of the Supreme Lord because a bona fide spiritual master presents the instruction of the Lord as they are. That is called to present and receive the instruction by disciplic succession. As we have this process described in the Bhagavad-gita, that the teachings of Bhagavad-gita should be received by disciplic succession, otherwise there is adulteration. So to act under the direction of such spiritual master and the motive being to satisfy the Supreme Personality of Godhead is pure devotional service. But as soon as one has motive for personal sense gratification, which are manifested in different ways-that the man is violent, proud, envious, angry and separatist. If one approaches to the Supreme Lord to render devotional service being proud of his personality or being envious to others, just to take revenge on others and in the mode of anger, and he thinks that he is the best devotee and others are not so, in this way if one executes the devotional service it is not pure devotional service; it is called mixed and the lowest grade: tamasaḥ. Srila Visvanatha Cakravarti Thakura has advised that the Vaisnava who is not of good character should be avoided. A Vaisnava means one who has taken the Supreme Personality of Godhead, Krsna or Visnu, as the ultimate goal of his life. He is to be considered a Vaisnava. But if he is not pure, if he has got still motives, then he is not a Vaisnava of the first order or good character. So to such Vaisnava one may offer his respect because he has accepted the Supreme Lord as the ultimate goal of life, therefore the respect of a Vaisnava should be offered to him, but one should avoid the company of such a low-grade Vaisnava in the modes of ignorance.