GEMARA: The mishna teaches that one who is suspected of relations with a gentile woman who later converted may never marry her. This implies that she is, however, a convert, although it appears that she converted only in order that he might marry her. The Gemara raises a contradiction from a baraita: Both a man who converted for the sake of a woman and a woman who converted for the sake of a man, and similarly, one who converted for the sake of the king’s table, so that he could serve in a prestigious capacity, or for the sake of Solomon’s servants, who were also considered prestigious, in all of these cases they are not converts; this is the statement of Rabbi Neḥemya.

There was another incident involving one gentile who was passing behind the study hall and heard the voice of a teacher who was teaching Torah to his students and saying the verse: “And these are the garments which they shall make: A breastplate, and an efod, and a robe, and a tunic of checkered work, a mitre, and a girdle” (Exodus 28:4). The gentile said: These garments, for whom are they designated? The students said to him: For the High Priest. The gentile said to himself: I will go and convert so that they will install me as High Priest. He came before Shammai and said to him: Convert me on condition that you install me as High Priest. Shammai pushed him with the builder’s cubit in his hand. He came before Hillel; he converted him.

But Ruth replied, “Do not urge me to leave you, to turn back and not follow you. For wherever you go, I will go; wherever you lodge, I will lodge; your people shall be my people, and your God my God.

When a [potential] convert comes to convert check after him, perhaps it is because of money he took, or because of power she will gain, or because of fear that [the pontential convert] is coming to enter the religion. And if he is a man, check after him perhaps he placed his eyes on a Jewish woman. And if she is a woman, check after her perhaps she placed her eyes on the single men of Israel. And if you do not find to them [such] a cause, inform them of the weight of the yoke of the Torah, and the difficulty of fulfilling it on the nations of the world in order that [the potential converts] leave. If they accept and do not leave, and you see them that they are returning out of love, accept them. And if you did not check after him or you did not inform him of the rewards of the commandments and their punishments, and he was circumcised and immersed before three ordinary people, this is a convert. Even if you are informed that it is because of some thing (like those discussed above) that he converted, since he was circumcised and immersed he has left the category of Idol Worshippers (i.e. Non-Jews), and we are worried for him until his righteousness is clarified. And even if he returns and serves Idols, he is like an apostate Israelite that his marriages are marriages. [Rama]: An apostate Israelite that repents does not need to immerse. Just that rabbinically he should immerse and accept words of joining (strict observance) before three.