The Custom of Saying Baruch Shepetarani
According to Rivkind this Geonic source shows that the main part of the Bar-Mitzva ceremony was reading the Torah and saying this blessing. Even more so he claims that this pushes the date of such ceremonies back to the time of the Geonim
Amongst Jews the customs widely vary with regards to saying this blessing. The reason for the differences is that the source of the custom is not a halachic source, instead it is from an Agadic source which in itself is somewhat terse since it says “from then on”.
The Levush had certain misgivings about this custom. He claims with regards to the blessing of Baruch Shepetarani that the reasoning behind it is not clear. Since if a child continues in his fathers transgressions, they are not exempted for many generations as it is said in the verse He (G-d punishes the children for the father’s transgressions . Therefore the Levush suggests making this blessing without the name of G-d or the kingdom.
The Ramah discussed this Levush in the Darkey Moshe and in his glosses to the Shulchan Aruch where he stated, “When somebody’s son has become Bar-Mitzvah he should bless … and it is better to say it without the name or kingdom. The Mishnah Brurah says that the opinion of the Grah is that since this blessing is mentioned in the Midrash, it should be said with the name and kingdom
There is additional discussion about the time and place of saying the blessing of Baruch Shepetarani. However, it is generally accepted amongst those who say it to say it at the time the Bar-Mitzva boy goes up to read the Torah.
There are generally three different customs with regards to saying this blessing. Amongst many Sephardim the custom is like the teaching of the Levush and Ramah that it is better to say this blessing without the name and kingdom. Many Ashkenazim also follow this method.
However, there are many others who follow the teaching of the Mishnah Brurah and the Grah who say that this blessing should be pronounced in its entirety. Personally, having an interest in the subject of Bar-Mitzvahs, I have seen most people pronounce this blessing without the name and kingdom.
The third custom is that of the Syrian community and undoubtedly others also not to even say this blessing at all. This is probably because it is not mentioned by Rabbi Yosef Karo in the Shulchan Aruch and also because it is mentioned nowhere in the Talmud.