King James Version of the Bible, Book of Proverbs, 13:24
"He that spareth his rod hateth his son: but he that loveth him chasteneth him betimes."
Due to the associated "spoil" concept which is not in the Bible, it more likely came from:
A 17th century poem by Samuel Butler called “Hudibras”. In the poem, a love affair is likened to a child, and spanking is mockingly commended as a way to make the love grow stronger. The actual verse reads [1]:
"What medicine else can cure the fits
Of lovers when they lose their wits?
Love is a boy by poets styled
Then spare the rod and spoil the child.