You'll regret in vain when you scorn good advice.
Who promises a lot will regret a lot.
Who got it, did get it; and who left it, did regret it.
Perform good deeds; you will not regret them.
One does not regret giving one's own ear-ring to one's dear friend.
Marry your children with their peers so you won't regret it someday.
I regret that I have given what I have.
Fret today, regret tomorrow.
Forgive and regret much later.