I've recommended a couple of friends for jobs, and I had reason to regret it... nothing serious, but enough to make me question the decision.
In one case, I told someone to use my name as a reference for freelance writing for my company. It was a different department than the one I worked in, and everything was going well for a while. Then one day someone tracked me down in the hall to say that they'd reached out to my friend but he hadn't responded or confirmed that he was going to meet a deadline. I was like, okay, I'll check with him. When I did, he said he hadn't realized he needed to reply to the email, as he intended to meet the deadline. I was like, Go write that email now! Not a big deal, but I was surprised that my colleagues (who I barely knew) would track me down. Also I was shocked that my friend wouldn't know the etiquette to respond to emails in the affirmative!
In another case (same company!), we were hiring for an open-ended temp position in my department, and I recommended a female friend that I knew was an awesome worker. My friend ended up having a major personality clash with my boss... again nothing blew up, but it felt awkward to me for most of the time we all worked together. It was clear that neither liked the other. My friend started dating someone else at the company while temping there, which was also noticed by my boss as friend would go on frequent breaks to chat with them. But, my friend was used to working much harder (and with much less supervision), and we didn't have all that much for her to do. Still, seeing her on yet another break as we all sat in our department meeting was... yep, weird.
After those experiences, I told myself I would never recommend anyone for a job again. Sharing these examples because I'd expect that many cases would more likely go wrong in a more spectacular way, but this was uncomfortable enough for me.
ETA: I should say that I'll never recommend someone for a job at a company where I am an employee! But I would give recommendations happily if they're applying to a different organization.