A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

in one’s book • in someone’s books
in one’s book —in the opinion of a person: In his book the
function of television was to edify, not to entertain.
Note: 
The expression does not correlate in meaning with the
phrase in the book—used of existing norms, laws, etc.: Although
Daisy entertained pretentious of grandeur, her dinner party
violated every rule in the book.
in someone’s books —(also: in someone’s good books) in favor
with a person: I was so much in his books, that at his decease
he left me his lamp.
in one’s day • on one’s day
in one’s day —(also: in one’s days) 
1
. during one’s lifetime:
And did not he [Bacon] cling to geocentricism, which was
still prevailingly current in his day? 2. in a period of one’s suc-
cess, prosperity, etc.: I know of one eminent man of science,
who was a burning and shining light in his day.
on one’s day —when performing as well as one can: On his
day he’s the finest goalkeeper in the country.
in one’s eyes • to one’s eyes
in one’s eyes —(also: in one’s eye) 
1
. in one’s imagination; in
one’s mind: I still have in my eyes the magic days spent on
the mountains with a lot of great people! 2. in one’s judgment;
in one’s view: For the life of him he could not make the thing
seem right or legal in his eyes.
to one’s eyes —(also: to one’s eye) as one sees it: To my eyes,
the most beautiful thing to paint is large vistas of land. The
land has its own harmony rich with shapes and with endlessly
changing colors.
in one’s grasp • within one’s grasp
in one’s grasp —said of smth. firmly controlled: President
Nixon stated that we now had in our grasp a peace with honor
instead of a peace with surrender.
within one’s grasp —said of smth. one is very likely to gain
or achieve: Just when the promised land seemed to be within
their grasp, the Greeks suffered ignominious defeat.