Wrongly Used Intellect:

Chana davened to Hashem to grant her “zera anashim" (a child of man, 1 Shmuel 1:11). Chazal (Brachos 31B) understand this to mean that she asked for a son who will be "not overly smart and not overly unintelligent." Why didn't she want a very smart child?

The Imrei Emes zy"a explains that Chana was a descendant of Korach (as Rashi says that Korach saw with ruach hakodesh that Shmuel would descend from him). When she thought about what occurred to such a smart man, she said that she wanted her own son to be of average intelligence.