A lot of people really need to get into the habit of doing this.

"Per our phone conversation earlier, my understanding is that you would like me to deploy the new update without any QA testing. As this may potentially create significant risks for our customers, I just want to confirm that I have correctly understood your instructions before proceeding."

If they try to call you back and give the instruction over the phone, then just be polite and request that they reply to your email with their confirmation. If they refuse, say "Respectfully, if you don't feel comfortable giving me this direction in writing, then I don't feel comfortable doing it," and then resend your email but this time loop in HR and legal (if you've ever actually reached this point, it's basically down to either them getting rightfully dismissed, or you getting wrongfully dismissed, with receipts).

Engineering prof in uni was big on journals/log books for cyoa and it's stuck with me, I write down everything I do during the day, research, findings etc, easily the best bit of advice I ever had.

Permanent records, please.

The issue with this is that a lot of companies have a retention policy that only retains emails for a particular period, after which they're deleted unless there's a critical reason why they can't be (eg to comply with a legal hold). It's common to see 2, 3 or 5 year retention policies.