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It would literally translate as "nobody throws stones against his own roof", the expression means that one person or in general any entity composed of persons, no matter what, is not going to make something that might cause damage, loss or, in general, any negative condition, to himself in a way he's aware of.
An example would be:
He's not going to lend that money to you, as he may need it later, and obviously [desired expression].
A reasonably close match is the idiom "shooting oneself in the foot", which refers to taking some self-destructive action.
Here, it fits well enough:
He's not going to lend that money to you, as he may need it later, and obviously he's not going to shoot himself in the foot like that.
Or, cleaned up a bit more:
He's not going to shoot himself in the foot by lending that money to you, as he may need it himself later.
In other cases, though, since the emphasis is more on the self-destructiveness than the implausibility, it may not fit as well to replace the Spanish idiom.
