Employer paying for MBA?

I hear companies sometimes pay for employees to pursue MBAs in return for the employee’s agreeing to stay with the company for a few years after getting the MBA.
How common is this practice?

Not as common as it used to be. My employer paid for my Wharton MBA in return for 5 years employment after finishing. If I left before the 5 years I would have had to repay the prorated cost to my employer…in a lump sum.

That was loooong ago though.