I promise you

I (can) promise you

I can guarantee with total confidence (that something is the case). If you don't accept this plea bargain, I can promise you that the judge is going to sentence you to life in prison if you're convicted. You will have such a rewarding experience if you go for this exchange trip, I promise you.
See also: promise
Farlex Dictionary of Idioms.

I (can) ˈpromise you

(informal) used as a way of encouraging or warning somebody about something: I can promise you, you’ll have a wonderful time. If you don’t take my advice, you’ll regret it, I promise you.
See also: promise
Farlex Partner Idioms Dictionary
See also:
  • I (can) promise you
  • I promise you!
  • hold (one's) end of the bargain up
  • hold (up) (one's) end of the bargain
  • hold end of the bargain up
  • keep (up) (one's) end of the bargain
  • keep (up) (one's) side of the bargain
  • get off easy
  • hard bargain
  • a hard bargain