Much like the 7th commandment (thou shall not commit adultery), this one basically says “keep your grubby paws of shit that isn’t yours”.
Exodus 20:15: “You shall not steal.”
It should go without saying that if it doesn’t belong to you, don’t take it. But apparently, for those who follow Christianity, it does need to be said.
Unlike the sky dude, I’m not going to judge you for accidentally pilfering the occasional small item … wandering off with a colleague’s pen, or absent-mindedly pocketing a friend’s cigarette lighter (let he who is without sin cast the first spliff, or something like that). But beyond that, keep your paws off.

Of course, if you get caught stealing you won’t always end up before the courts. White collar criminals committing fraud generally get dealt with much more gently than some poor sod caught nicking food for their kids from the local supermarket.
Although, when there are so many people struggling to feed their families these days, those of you who aren’t struggling could do a little more to help. Even if it’s just donating a couple of cans of beans to the local food bank.
But generally, if it isn’t yours, don’t take it.
Don’t be a thieving cunt.
Back to the Big Book of Shagging, Smiting and Slaying’s top 10 rules