冇咁大個頭就唔好帶咁大頂帽 (mou5 gam3 daai6 go3 tau4 zau6 m4 hou2 daai3 gam3 daai6 deng2 mou6) — one can only spend as much as one can afford; one should not over stretch beyond their limits / power / abilities; to not bite off more than one can chew [colloquial] in Cantonese
mouˏ₅冇gam˗₃咁daaiˍ₆大go˗₃個tauˎ₄頭zauˍ₆就mˎ₄唔houˊ²好daai˗₃帶gam˗₃咁daaiˍ₆大dengˊ²頂mouˍ₆帽简 冇咁大个头就唔好带咁大顶帽
Mandarin Pinyin: mao3 gan1 da4 ge5tou2 jiu4 wu2 hao3 dai4 gan1 da4 ding3 mao4
Meaning of 冇咁大個頭就唔好帶咁大頂帽
nounone can only spend as much as one can afford; one should not over stretch beyond their limits / power / abilities; to not bite off more than one can chew [colloquial]