Question: While praying the synagogue on Shabbat morning, may I speak with my friend while the Torah is being read?
Answer: The Gemara (Sotah 39a) states: “Rabba bar Rav Huna said: As soon as the Sefer Torah is opened, one may not even speak words of Halacha, as the verse states, ‘And when it was open, the entire nation stood,’ and standing refers to being silent. Rabbi Zera said that Rav Chasda derived this law from the verse, ‘And the ears of the nation were toward the Sefer Torah.’”
This means that as soon as Torah reading begins in the synagogue, one may not engage in even a Torah conversation and certainly not idle chatter. This Halacha is derived from the fact that Ezra the Scribe opened the Sefer Torah, and the entire nation was silent so they could concentrate on what was being read.
The Letter of the Law
The Rishonim speak about some different details regarding this law. Maran Ha’Shulchan Aruch (Chapter 146) rules:
“Once the reader begins reading the Torah portion, one may not speak even words of Torah, even in between the Aliyot.”
Although there are different opinions regarding the studying Torah between the Aliyot and even while the Torah is being read, all opinions agree that random conversation between two people is strictly prohibited, both during the reading and between the Aliyot.
Speaking Between the Aliyot
The students of Rabbeinu Yonah explain that speaking between the Aliyot is likewise prohibited because the Sages were concerned that this might lead to speaking during the actual Torah reading as well. Nevertheless, briefly replying to a halachic question in between the Aliyot is permissible. (See Mishnah Berurah, Subsection 6)
The Ma’amar Mordechai writes that the prevalent custom is that when a groom or Bar Mitzvah boy is present in the synagogue that the congregation sings in their honor before they go up to read the Torah. This custom has a solid basis, for there is no concern that the congregation will continue singing even after the Torah begins to be read.