Translation - Farsi-Persijski jezik-Turski - دولت ابد مدت

it's not a complete sentence. but also not just three seperate words. it's a conjuction, a noun phrase joint. this joint of phrase is used in persian language so turks use it their literature as their type of phrase joint. it means about "nation of eternal duration". this is not the exact translation of course but similar at least.

OK I think I undrstand what you mean, I'll validate it

Is this Turkish? It looks like it's simply a transcription of the Arabic words into their Turkish spelling. What does it mean?

yes, it's Turkish. of course each of the words in the phrase is Arabic in root. but gramatic of the phrase is not Arabic. that's Persian. "devlet-i ebed müddet". and its usage has a place in Turkish literature. it means "infinit state" or something like this.

Thanks - that means the German translation is incorrect.

which means that the original phrase is not arabic, its true, each word sounds arabic, but together they mean nothing...
Dawlat (wrong spelling as well) means country or state
Abad: Ever or eternity
Maddat: stretched or extended
but they dont work together

So it's a Persian phrase written in an inaccurate Arabic.

I guess it's not Arabic at all - it is apparently written in Farsi, or even Ottoman Turkish.

I changed the source language to Farsi.