xxi.), that Abraham's guests went not away until "he had made
them proselytes, and had taught them the way everlasting." His
son Isaac, says the Targ. of Ben Uzziel, went to school at the
"Beth Medrasha de Shem Rabba."

Though Abraham kept all the commandments, he was not perfect till he was
circumcised.

_Nedarim_, fol. 31, col. 2.

In whatever sense this may have been written, and whatever the
interpretation that may be put upon it, there is one sense in
which it is absolutely and eternally true, and that is, that, in
order to be perfect, a man's life must be as pronounced on the
negative side as the positive, in its denials as in its
affirmations, and that it is futile to attempt to obey God
unless one at the same time renounce all co-partnery with the
devil. Circumcision is the symbol of this renunciation, and it
is only as such it has any radical spiritual significance. Till
he was circumcised, it is said, God did not speak to Abraham in
Hebrew. Not till then is sacredness of speech, any more than
sacredness of life, possible. Doubtless among the Jews
circumcision was the symbol of their separation from the ethnic
religions; and hence the jealousy with which their prophets
looked upon any compromise with idolatry. Hatred of that, utter
and intense, was the one essential negative pole of genuine
Judaism, and circumcision was its sign and seal.

Abraham was the first of the proselytes.