且不說

且不说
qiěbùshuō
  1. not to mention
  2. leaving aside

CEDICT

let alone; not to mention; much less

Wiktionary

Entry Composition

1 且 qiě
  1. and
  2. moreover
  3. yet
  4. for the time being
  5. to be about to
  6. both (... and...)
2 不 bù
  1. no; not so
  2. (bound form) not; un-
3 說 shuō
  1. to speak; to talk; to say
  2. to explain; to comment
  3. to scold; to tell off
  4. (bound form) theory; doctrine

Related entries

慢說 mànshuō not to mention ... (i.e. in addition to sth)
漫說 mànshuō not to mention ... (i.e. in addition to sth)
遑論 huánglùn
  1. let alone
  2. not to mention
波士頓對我來說已經太冷了,更遑論是芝加哥。

Boston is too cold for me, let alone Chicago.

Source: Tatoeba