Philostratus quotes
The votaries of Pythagoras of Samos have this story to tell of him, that he was not an Ionian at all, but that, once on a time in Troy, he had been Euphorbus, and that he had come to life after death, but had died as the songs of Homer relate. And they say that he declined to wear apparel made from dead animal products and, to guard his purity, abstained from all flesh diet, and from the offering of animals in sacrifice. For that he would not stain the altars with blood; nay, rather the honey-cake and frankincense and the hymn of praise, these they say were the offerings made to the Gods by this man, who realized that they welcome such tribute more than they do the hecatombs note and the knife laid upon the sacrificial basket.
Philostratus
Apollonius accordingly paused for a minute and then, fixing his eyes, as it were, on the discourse he had heard, he spoke as follows: "... I am not come here to ask your advice about how to live, insomuch as I long ago made choice of the life which seemed best to myself ... For I discerned a certain sublimity in the discipline of Pythagoras, and how a certain secret wisdom enabled him to know, not only who he was himself, but also who he had been; and I saw that he approached the altars in purity, and suffered not his belly to be polluted by partaking of the flesh of animals and that he kept his body pure of all garments woven of dead animal refuse; and that he was the first of mankind to restrain his tongue, inventing a discipline of silence ... I also saw that his philosophical system was in other respects oracular and true. So I ran to embrace his teachings ..."
Philostratus
Now Euxenus realized that he was attached to a lofty ideal, and asked him at what point he would begin it. Apollonius answered: "At the point at which physicians begin, for they, by purging the bowels of their patients prevent some from being ill at all, and heal others." And having said this he declined to live upon a flesh diet, on the ground that it was unclean, and also that it made the mind gross; so he partook only of dried fruits and vegetables, for he said that all the fruits of the earth are clean. And of wine he said that it was a clean drink because it is yielded to men by so well-domesticated a plant as the vine; but he declared that it endangered the mental balance and system and darkened, as with mud, the ether which is in the soul. After then having thus purged his interior, he took to walking without shoes by way of adornment and clad himself in linen raiment, declining to wear any animal product.
Philostratus