Srila Narottama dasa Thakura says:
cittete kariya aikya
One should accept a thing as genuine by studying the words of saintly people, the spiritual master and the sastra. The actual center is the sastra, the revealed scripture. If a spiritual master does not speak according to the revealed scripture, he is not to be accepted. Similarly, if a saintly person does not speak according to the sastra, he is not a saintly person. The sastra is the center for all.
(Sri Caitanya-caritamrta 20.352 Purport)