The prophetic reading traditionally paired with the Torah portion at many bar mitzvah services is called the haftarah.
A haftarah is a selected passage from the Nevi’im, the Hebrew Bible’s books of the Prophets. It is read after the weekly Torah portion in many Jewish congregations, especially on Shabbat and festivals. A bar or bat mitzvah celebrant may chant the haftarah and its accompanying blessings as part of the service.
The passage is usually connected thematically to the Torah portion or to the occasion. The exact text and chanting tradition can vary according to the congregation’s calendar and custom. Some communities omit or modify the reading in particular services.
Haftarah is not the same as a d’var Torah. The haftarah is a scriptural reading, while a d’var Torah is a teaching or interpretation. Nor is it the Torah portion itself, which comes from the Five Books of Moses.