Long story short, last Friday my boss told me we needed to release a new version of our ship application as soon as possible that day, without previous noticing. I told him it wasn't properly tested yet, and since the last changes I made were basically "prone to errors" (especially because they were microoptimizations I couldn't test enough and could break the code easily).
I encouraged my boss to postpone the release for Monday, since if there was any kind of error, I wouldn't be able to fix it. Or at least, place this update into a beta stage, where only I am able to test it. However, the way beta and production stages work with mobile apps means we had to be waiting there a lot more than expected, so he wanted to release it straight to production.
After that, he also told me it was pretty important I finished another task before leaving, so I had one hour overtime on Friday to finish a task for Monday morning.
Obiously, the app crashed. It crashed right after I left the office on Friday, and our ratings went down a lot. He saw this on Saturday and called me at home, after lunchtime, asking me to guide him on how to solve this on the phone. I wouldn't say he isn't capable, but I was totally unable to do that from memory, so I had to go to the office and spend another hour of my free time there, fixing an issue I encouraged him to avoid.
Also, during today (Monday), he's come to my desk, asking me to keep the same schedule we had last Friday, but also applying more improvements to this. This means that I won't have my two hours off (since I already worked on them during Fri and Sat) today, and probably not tomorrow as well.
I have a bad taste since it happened the same to me in my previous job: the boss felt fine to make me work overtime without paying the hours or letting me be off earlier, since there were more tasks everyday. Worse than that, despite forcing me to come to the office on a Saturday, he didn't apologize in any way (for either calling me, or having taken a decision that force both of us to go to the office on Saturday). Instead, he kind of put more pressure by tightening the schedule even more.
In a situation like this, which will definitely end up burning me, and where the boss clearly wants to rush even at a cost none of us is willing to pay, how can I tell him to, let's say, stand back and trust my expertise?
I'm in Spain, hired for 39 hours/week, no paid overtime (instead, any extra hour done is compensated with an hour off in the following days).