Reference for Berakhot 123:9

רבא מקמי דהוי רישא מקרקשא ליה בת רב חסדא אמגוזא בלקנא בתר דמלך עבדא ליה כוותא ומנחא ליה ידא ארישיה

Before Raba was appointed Principal [of the Seminary], the daughter of Rab Hisda used to rattle a nut in a flask for him; but afterwards when he ruled [over the Seminary] she made an aperture for him [in the wall] and placed her hand upon his head.

Jastrow

Jastrow