Swaying a prayers (מנוד ראש)
Possibly the habit of swaying at prayers, mentioned by Judah ha-Levi in the "Cuzari" (ii. 79, 80), was known in the academies as a custom performed during learning, was transplanted into the synagogue. Shmuel ha-Nagid (eleventh century) speak of the practice of swaying while studying. The Talmud Shabbat 104a, specifically mentions swaying of the head during prayers, using the word manud rosh. The Arabic lexicographer Fikh al-lugha explain nawadan (= Hebrew נוד) as "to shake," and applied it to the Jewish mode of shaking the person at prayer or study.
This custom must be a strictly Babylonian custom that was not approved of by Muslims. A haddith refers disparagingly to the shuckling, rocking back and forth, of Jews as the shaking of sheep.