Not my parent, but a life lesson that serves me well.
As an apprentice my first boss was my father's best mate, he was a little guy who wore glasses he smoked a pipe constantly and was often referred to as "popeye"
As a young man I resented him, I was bitter towards him and believed he was nasty and unfair. He would often (what at the time felt cruel to me) work me hard, give me all the s**t jobs no one else would do. He showed me no slack and would come down on me for poor time keeping (even a minute late), extended breaks, chatting at work... I was constantly bitter with him, he would often comment "do you hate my guts?" I'd always reply "yes" and he would walk off smiling. A few years later when I'd matured and gained some experience, I noticed that his attitude started to change towards me. A few years later on completion of my apprenticeship he came and had a chat with me.
He sat me down and said, "you know one day this business will be yours if you want it" I was shocked and taken aback. Unfortunately he died before this ever came to be and his wife sold the business on to his rival.
Looking back as I'm nearing a similar age to when he passed, I often consider his approach. It was cruel to be kind, he was preparing me for life, he was actually nurturing me to be his successor in a way that would be frowned upon these days. I have the upmost respect for him and actually missed him really bad when he passed away.
Sometimes tough love is the best kind of love.