Asalamu 3alykum
Dear Miracle114
You asked
Is there such a concept in the Quran?
I assume you are asking if there is any Valid/Invalid Salah?
The Quran does seem to stipulate certain mandatory requirements that should be part of ones daily prayers. Please see the article below
[1]. It also seems to curtail certain acts when it comes to prayer (8:35)(17:110). As you may notice this forum Masha'Allah speaks volumes about the format of the Salah and what one is entitled to do while praying.
In my humble opinion, anything beyond what is detailed in the Quran about prayer should not be seen as a lack of details but as a mercy and flexibility from the Lord to accommodate ones needs.
However it is also important to note that if a requirement such as prayer has already been established or is in-situ without conflicting with the Quran then there is also a good suggestion to assimilate and enjoin with those who do it(2:43, 3:43). There does not seem to be any wisdom to re-invent something that is correctly been established.
Traditional schools have an array of conditions regarding whether one's salaah is valid or not.
Insha'Allah as people get more and more familiar with the Quran then it will become easier to recognize what seems to be in light of the Quran's spirit and what is not.
As an example, if your back shows a little as your top rides up in prostration.
While observing the general basic fundamentals of prayers, no one can really say if a prayer is valid or invalid except the Good Lord. He only knows who are trying their hardest and He only knows peoples intentions.
Although the Quran does not detail every fine element of how prayer should be performed, there is some acts that can be seem as not being in the spirit or light of the Quran's overall message. I personally find that ones back should be covered if they feel it is exposed or make preparations to cover it before prayer if they can given everyones situation.
One thing for sure is that people are expected to do their duties as best as they can. Unfortunately it maybe that some people in the world don't have proper clothes. But their prayers reach the Lord. Some are in fear some are secure. Whatever the situation one should do their duties as best as they can.
64:16 So keep your duty to Allah as best ye can, and listen, and obey, and spend; that is better for your souls. And whoso is saved from his own greed, such are the successful.As I know it salaah is an obligation we owe ourselves not Allah the Almighty.
It is indeed going to benefit a person Insha'Allah but ultimately in my humble opinion prayer, remembrance, obligations, are for Allah(swt). I believe we owe it to Allah(swt) and need to glorify Him for having guided us.
Salam
A SIMPLE INSTRUCTION CONFOUNDS MANY - 'ESTABLISH SALAAT'https://www.facebook.com/joseph.a.islam/posts/487157614754704