I've come across a saying "The more you sweat in peace, the less you bleed in war". I'm curious how this would be expressed in Irish. Is there a seanfhocal with the same kind of meaning?

My attempt at an Irish version in a similar vein is:
Is fearr allais a chur fé shíocháin ná fuil a chur ag cath

I'm learning the Corca Dhuibhne dialect so any region-specific words or saying would be ideal.

Small detail

Allas a chur would be used here
(But, ag cur allais)

Difference of the 'i.'

The Irish is otherwise correct, but sorry I'm not sure if there'd be any better way to phrase it.

There is a structure: dá fheabhas.... is ea is feárr é.

Dá mhéid allais a chuireann tú fé shíocháin is ea is lú-de an fhuil a theilgfidh tú i gcath.

[I spelt lúide lú-de.]

There is some uncertainty and variance as to whether genitive after dá mhéad should be used. Some prescriptive grammars prescribe nominative: dá mhéad allas.
But both can be found: dá mhéad allas / allais

Both dá mhéad and dá mhéid are used. In Munster, dá mhéid is probably more common.
I wonder whether there is a slight difference in meaning (however big vs. however much).

I wonder whether lúide (lú-de) is correct here. At least I could not find any other example.*
… is ea is lú an fhuil a theilgfidh tú i gcath or
… is ea is lú a theilgfidh tú fuil i gcath is sufficient.


*) There was an older form dá … is lúide … but without is ea

Labhrás, you are right. It is dá mhéid +nominative. Sorry about that. dá mhéid allas. And right on the point about lú, rather than lú-de. Sorry about that too.

Labhrás, I've just come across an example of other structure you mentioned, with -de, but not "ea" - thanks for explaining it. Here's the example:

This is from Quo Vadis (Aindrias Ó Céileachair). The English version says:

Interesting.
Thank you for citing.

I wonder if the last é is grammatically correct in this sentence.
I'd think -de in fearrde is referring back to dá theocht é, so no further reference point is needed:
Dá theócht é is feárrde gach a mbeathaíonn sé (é?).
It would be a doubled reference.

In a "normal" -de sentence (without dá theocht) -de is usually referring forward:
Is fearrde thú Guinness.
Ní troimide an loch an lacha.
So, if I'd use our sentence without the dá part, é would be permitted:
Is fearrde gach a mbeathaíonn sé é.

People do include it in speech whenever I've heard it.

My intuitive grasp would be that in:
Dá theócht é is feárrde gach a mbeathaíonn sé é

The sentence would translate as:
"As it is warmer, so the better all that it rears"

I don't know the full history of the "fearrde" form, but speakers today consider it a form of "maith" as such. "All the better" or "so the better". Hence they wouldn't see the -de as referring to "Dá theocht é", rather they would see "is feárrde gach a mbeathaíonn sé é" as a copular clause needing the "é". Basically they see it as your last sentence with the "Dá" clause introducing it.

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The dialect I use is Cork Irish.
Ar sgáth a chéile a mhairid na daoine, lag agus láidir, uasal is íseal

I see the normal syntax as:
is feárrde mise é - I am the better for it
The é refers back to dá theócht é
I get what you mean that dá theócht é is already referred back to by -de, but this is the standard syntactical pattern

This is from Father Peter's Lúcián:

You are not any better off for saying things like that and I am not any better off for listening to it.

I think the [cainnt den tsórd san do labhairt] slot is basically out of construction (using O'Nolan's phrase for a phrase not properly linked to the rest of the sentence). I think you could imagine a "with respect to" or even an "agus" in there:

Ní fearrde thusa [AGUS] cainnt de'n tsórd san do labhairt, agus ní fearrde mise [AGUS] éisteacht leis an gcainnt

You are not [better off for it] [on account of] saying such a thing.

É then fills the slot when you remove the out of construction phrase.

It is actually similar to the way in which you have to have é in "ní féidir é". This is Father Peter's explanation from Notes on Irish Words and Phrases:

I don't know if there are dialectal differences in the use of the final é - that is another can of worms...