In the previous Halachot we have explained the laws of rising before a Torah scholar and an elderly man.
Halacha dictates that one should not show honor to a student in the presence of his rabbi, meaning that if there are two Torah scholars in front of an individual and one is the rabbi of the other, one should not show honor to the student in the presence of the rabbi (however, one may certainly degrade him or withhold honor that will cause him to be humiliated). Nevertheless, if the rabbi himself shows honor to the student, one may show honor to the student in the presence of his rabbi.
In a similar vain, when one shows honor to Hashem, it seems that if at the same time one’s rabbi appears before him, one should show honor to one’s rabbi. For instance, if one is sitting in the synagogue reciting Keri’at Shema and its blessings or Pesukei De’Zimra, one must nevertheless rise completely to one’s full height for an elderly man or a Torah scholar who is passing by. Although one is showing honor to Hashem while reading Keri’at Shema and the like and it seems improper to show honor to a rabbi at this time, for the rabbi is considered a student in the presence of his rabbi with respect to Hashem, nevertheless, since Hashem himself has commanded us to rise before an elderly man or a Torah scholar, this is similar to the rabbi showing honor to the student in which case one should likewise show honor to the student in the presence of the rabbi. Maran Ha’Chida writes likewise in his Birkei Yosef.
The same applies to one who is reciting Birkat Hamazon and sees an elderly man or a Torah scholar passing within one’s four Amot in that one must rise in their honor (although Birkat Hamazon retains the same law as the Amida prayer with regards to greeting someone and thus, one may not reply “Shalom” or “Hello” even to a highly-respected individual while reciting Birkat Hamazon as opposed to one reciting Keri’at Shema, nevertheless, one must rise for an elderly man while reciting Birkat Hamazon, for rising silently is not considered an interruption).
Indeed, Hagaon Harav Yosef Chaim Zonnenfeld zt”l was asked about this in the following manner: “Should one reciting Keri’at Shema and its blessings fulfill the Mitzvah of rising for a Torah scholar or an elderly man, for it is possible that we should be concerned for a human being’s honor not being greater than Hashem’s honor since the individual is involved in accepting the yoke of Heaven?” Hagaon Harav Zonnefeld replied: “The same Hashem who has commanded us to recite Keri’at Shema has likewise commanded us to rise before Torah scholars and by doing so, one will only be doing what one was commanded to do.” This ruling is the same as that of Maran Ha’Chida. Maran Rabbeinu Ovadia Yosef zt”l rules likewise.