Amidah-Shaking While Praying-Shelah

The 11th of Nisan is the Yahrtzeit of Rav Yeshayah Horowitz, author of Shnei Luchos Habris: Shaking in prayer causes one to lose concentration, while standing motionless enhances it. The verse, “All my bones shall say,” is speaking of other prayers, but not the Amidah, where one must stand motionless. We see him practice that standing motionless enhances one’s meditative concentration. (Sh’nei Luchot HaBrit; Amud HaTefillah 2:203a)