Mbh 13.37.4a

"'Bhishma said, "If the Ritwik, the Purohita, the preceptor, the Acharya, the disciple, the relative (by marriage), and kinsmen, happen to be possessed of learning and free from malice, then should they be deemed worthy of respect and worship. Those persons that do not possess such qualifications cannot be regarded as worthy of gifts or hospitality. Hence, one should with deliberation examine persons with whom one comes into contact. Absence of wrath, truthfulness of speech, abstention from injury, sincerity, peacefulness of conduct, the absence of pride, modesty, renunciation, self-restraint, and tranquillity or contentment of soul, he in whom these occur by nature, and in whom there are no wicked acts, should be regarded as a proper object. Such a person deserves honours. Whether the person be one who is well-known and familiar, or one who has come newly, whether he has not been seen before, if he happens to possess these qualifications, he should be regarded as worthy of honours and hospitality. He who denies the authority of the Vedas, or strives to show that the scriptures should be disregarded, or approves of all breaches of restraint in society,--simply brings about his own ruin (and should not be regarded as worthy of gifts). That Brahmana who is vain of his learning, who speaks ill of the Vedas or who is devoted to the science of useless disputation, or who is desirous of gaining victory (in disputations) in assemblies of good men by disproving the reasons that exist for morality and religion and ascribing everything to chance, or who indulges in censuring and reproaching others or who reproves Brahmanas, or who is suspicious of all persons, or who is foolish and bereft of judgment, or who is bitter of speech, should be known to be as hateful as a dog. As a dog encounters others, barking the while and seeking to bite, such a person is even so, for he spends his breath in vain and seeks to destroy the authority of all the scriptures.