On the fiftieth day, Higher Shekhinah resides upon Her, and She is called ‘the Giving of the Torah’.
And the Middle Pillar is the Torah, that is given on the fiftieth day, on the Festival of Weeks, and about it is stated: ‘Fifty years for old age’ (ziqnah), [Var. for ‘understanding’] of that of which it is stated: (Prov. 23:22)... your mother when she has aged.
And of Her it is stated: (Prov. 2:3) For if or ‘a mother’ to understanding (binah) you will call... (Prov. 2:3) Because She is the letter Hei ה, and ascends through the letter Yod י (=10) to fifty – five times ten, and of that it is stated: ‘Fifty years for old age’, of that of which it is stated:... do not despise your mother when she has aged. (Prov. 23:22) [Vav is ‘son’ of Y-Q]