The Vīmaṃsaka Sutta (MN 47, The Inquirer) is the 47th discourse within Majjhima Nikaya of Pāli Canon in Theravada Buddhism and paralleled by 求解 ('The discourse on investigating [for the sake of] understanding', MA 186 T 26.186) in the Madhyama Agama of the Chinese Taisho Tripitaka.
According to Bhikkhu Analayo, this sutta and its Chinese parallel presents "a remarkable advocacy of free inquiry" by making the Buddha's claim to awakening the object of "the most searching scrutiny.
"[1] The sutta outlines the various ways that one can evaluate the Buddha himself (and by extension any spiritual teacher) to determine if their teaching is genuine and if they are truly liberated.
The Buddha also encourages a monk to directly ask him about his mental states thus: ‘Are there found in the Tathāgata or not any defiled states cognizable through the eye or through the ear?’ Other questions that the student should investigate include whether the teacher attained his current state long ago or only recently (in the Chinese version this question is whether he has been practicing in a wholesome way for a long time or not) and whether he practices for the sake of fame or gain.
Thus, while doubt (vicikiccha) is seen as an obstacle and a hindrance to Buddhist practice, it is to be removed by a process of personal critical inquiry.