畏首畏尾

wèishǒuwèiwěi
  1. afraid of the head, terrified of the tail (idiom); ever fearful and nervous
  2. afraid of the slightest thing

CEDICT

to be afraid of the slightest thing; ever fearful and nervous; to be full of misgivings; to be overcautious

Wiktionary

顾前顾后，十分戒慎恐惧的样子。《左传．文公十七年》：「古人有言曰：『畏首畏尾，身其馀几。』」《幼学琼林．卷二．身体类》：「恐惧过甚，曰畏首畏尾。」也作「畏头畏尾」。

重編國語辭典

形容疑虑顾忌，胆小怕事

維基詞典

Entry Composition

1 畏 wèi to fear
2 首 shǒu
  1. head
  2. chief
  3. first (occasion, thing etc)
  4. classifier for poems, songs etc
3 畏 wèi to fear
4 尾 wěi
  1. tail
  2. remainder
  3. remnant
  4. extremity
  5. sixth of the 28 constellations
  6. classifier for fish