Midrash su Levitico 19:34

3) (Vayikra 19:34) ("As the home-born among you shall he be to you, the stranger that lives among you." And you shall love him as yourself, for you were strangers in the land of Egypt; I am the L–rd your G d.") "As the home-born": Just as the home-born takes upon himself all the words of the Torah, so, must the proselyte take upon himself all the words of the Torah. From here they ruled: If a proselyte took upon himself all the words of the Torah except one, he is not to be accepted. R. Yossi b. R. Yehudah says: Even (if he did not accept) a small thing of the inferences of the Scribes.

4) "shall be to you the stranger that lives among you. And you shall love him as yourself." Just as it is written of Jews (Vayikra 19:18) "and you shall love your fellow as yourself," so is it written of proselytes "and you shall love him as yourself." "for you were strangers in the land of Egypt": Know the soul of the strangers, for you yourselves were strangers in the land of Egypt."

(Exod. 19:1:) ON THE THIRD NEW MOON. What is written above on the matter? The parashah about Jethro, in which he taught Moses (in Exod. 18:21): YOU SHALL ALSO SEEK OUT <ABLE MEN> FROM AMONG ALL THE PEOPLE.³²PRK 12:16. And after that (in vs. 27): THEN MOSES SENT HIS < FATHER-IN-LAW > AWAY. And after that (in Exod. 19:1): ON THE THIRD NEW MOON. Solomon said (in Prov. 14:10): THE HEART KNOWS ITS OWN BITTERNESS…, and therefore (according to the rest of the verse) NO OUTSIDER SHALL INTERVENE IN ITS JOY. The Holy One said: My children were enslaved with clay and bricks while Jethro was dwelling quietly within his house. So shall he come to behold the joy of the Torah along with my children? Then after that (in Exod. 19:1): ON THE THIRD NEW MOON. Why so? Moses interpreted <the matter on the principle of > qal wahomer (i.e., a fortiori): If in the case of a single precept, when the Holy One was going to give the precept on Passover, Torah said (in Exod. 12:43): NO FOREIGNER SHALL EAT OF IT; in the case of six hundred and thirteen commandments which he wanted to give to Israel, should Jethro be there to behold them? Therefore (in Exod. 18:27): MOSES SENT HIS <FATHER-IN-LAW> AWAY; and after that (in Exod. 19:1): ON THE THIRD NEW MOON. Why ON THE THIRD NEW MOON, and not on the second new moon, or the seventh new moon, or on another new moon?³³PRK 12:17. Our masters have said: R. Osha'ya said: R. Hiyya the elder taught me: A female proselyte, a female captive, or an emancipated female slave may neither marry nor be betrothed for three new moons.³⁴Yev. 35a (bar); Ket. 37a (bar). So <it was with> Israel. They were called proselytes (gerim), as stated (in Lev. 19:34): FOR YOU WERE STRANGERS (gerim) IN THE LAND OF EGYPT. <They were called> captives, as stated (in Is. 14:2): THEY SHALL TAKE THEIR CAPTORS CAPTIVE. <They were called> emancipated slaves, as stated (in Lev. 26:13): I AM THE LORD YOUR GOD WHO BROUGHT YOU OUT OF THE LAND OF EGYPT TO BE THEIR SLAVES NO MORE…. The Holy One said: I will wait three new moons for them and after that I will give them the Torah.