'Ninety nine' in the Bible

Tell me, if a man has a hundred sheep and one of them strays, will he not leave the ninety-nine sheep on the hills and go in search of the one that has strayed?

And if he happens to find it, I tell you he rejoices over it more than over the ninety-nine that never went astray.

"Which of you with a hundred sheep, if he loses one, does not leave the ninety-nine in the desert and go after the lost one till he finds it?

So, I tell you, there will be joy in heaven over a single sinner who repents, more than over ninety-nine good people who do not need to repent.