Language has rules we are use to so that we understand one another.
13:7 although linguistically is open for interpretation the following proves there is one possible interpretation that is rational by language rules and contextualization.
Linguistic rules
The first thing to be said, is that, there is two more meanings I can think of then that every people have a guide. One is that Mohammad (s) is for every people a guide. And another is that were will one day be for every people a guide.
However, these two are not rational to hold, since if those were intended, a more clearer way of saying for example, if Mohammad (s) was intended as the guide for every people, all that needed to be said, was "and for every people the guide". And "al" would have made it clear that Mohammad (s) was intended to be the Guide for every people.
If it referred to a guide in the future for all people, all that needed to be said, was "and there will be...." and it would be clear.
Language rules is that when a phrase can be said much clearer in a way that is not the impression given by the phrase, you must not assume the other meanings but rather go with what the first impression is. Unless the first impression is impossible or context of other words imply it's not what is meant, you must go with the first impression.
After all this is how we engage the verse with seal of Prophets, or all sorts of meanings alternative to the first impression can be made up.
Now that this has been said, there is further reasons that it means for every people there is a guide.
Context is about miracles and proofs.
The context is about why not a proof or sign brought, and so the topic being on that, it makes sense more in line to say, you are only a warner while before you and after you there is always a guide that can perform such miracles.
This more in line with the context, and talking about Mohammad (s) being a guide for all people is off-topic. Although it's true, and same with there being a guide for every people at the end times who they will accept (the Mahdi) are both off-topic.
Rather, in line with the "You are only a warner" is to say furthermore, which is the meaning of the and in this context, furthermore it is the case that for every people there is a guide who can brings such signs and who the signs prove their case.
Theme of "you are only a warner"
Aside from that, Quran has a style when saying "You are only a warner", and it replies with facts that compliment that. Mohammad (s) being sent for the whole world or the Mahdi (a) being a guide at end times, are both, again, not complimenting this at all. The "and" is suppose to be said in the spirit of it, it has the nature of the "furthermore" and not "as well it is the case that". It's obvious if you see all the verses and keep them in mind of "you are only a warner", the next phrase after the "Wa" is always in spirit of furthermore type "and".
The witness, the leader we be called with theme
Aside from that, there is a whole theme in Quran about every people having a witness and another verse says the witness is a leader, by saying "the day every human is called with their leader". There is a verse that says the day every people come with a driver and a witness as well.
So in spirit of that, this is saying the witness is the Guide of the people of his time, and compliments it.
Authentic hadith verifies the meaning.
So we have these 4 reasons to see that. But aside from that there is hassan or Sahih sunnni hadith that it means that the guide is a man from Bani-Hashim. The excuses that this refers to Mohammad (s) is again denied by the way language works, rather, it means, there will be for every people a guide from bani-hashim.
So we have hadith that verifies the meaning as well.
13:7 although linguistically is open for interpretation the following proves there is one possible interpretation that is rational by language rules and contextualization.
Linguistic rules
The first thing to be said, is that, there is two more meanings I can think of then that every people have a guide. One is that Mohammad (s) is for every people a guide. And another is that were will one day be for every people a guide.
However, these two are not rational to hold, since if those were intended, a more clearer way of saying for example, if Mohammad (s) was intended as the guide for every people, all that needed to be said, was "and for every people the guide". And "al" would have made it clear that Mohammad (s) was intended to be the Guide for every people.
If it referred to a guide in the future for all people, all that needed to be said, was "and there will be...." and it would be clear.
Language rules is that when a phrase can be said much clearer in a way that is not the impression given by the phrase, you must not assume the other meanings but rather go with what the first impression is. Unless the first impression is impossible or context of other words imply it's not what is meant, you must go with the first impression.
After all this is how we engage the verse with seal of Prophets, or all sorts of meanings alternative to the first impression can be made up.
Now that this has been said, there is further reasons that it means for every people there is a guide.
Context is about miracles and proofs.
The context is about why not a proof or sign brought, and so the topic being on that, it makes sense more in line to say, you are only a warner while before you and after you there is always a guide that can perform such miracles.
This more in line with the context, and talking about Mohammad (s) being a guide for all people is off-topic. Although it's true, and same with there being a guide for every people at the end times who they will accept (the Mahdi) are both off-topic.
Rather, in line with the "You are only a warner" is to say furthermore, which is the meaning of the and in this context, furthermore it is the case that for every people there is a guide who can brings such signs and who the signs prove their case.
Theme of "you are only a warner"
Aside from that, Quran has a style when saying "You are only a warner", and it replies with facts that compliment that. Mohammad (s) being sent for the whole world or the Mahdi (a) being a guide at end times, are both, again, not complimenting this at all. The "and" is suppose to be said in the spirit of it, it has the nature of the "furthermore" and not "as well it is the case that". It's obvious if you see all the verses and keep them in mind of "you are only a warner", the next phrase after the "Wa" is always in spirit of furthermore type "and".
The witness, the leader we be called with theme
Aside from that, there is a whole theme in Quran about every people having a witness and another verse says the witness is a leader, by saying "the day every human is called with their leader". There is a verse that says the day every people come with a driver and a witness as well.
So in spirit of that, this is saying the witness is the Guide of the people of his time, and compliments it.
Authentic hadith verifies the meaning.
So we have these 4 reasons to see that. But aside from that there is hassan or Sahih sunnni hadith that it means that the guide is a man from Bani-Hashim. The excuses that this refers to Mohammad (s) is again denied by the way language works, rather, it means, there will be for every people a guide from bani-hashim.
So we have hadith that verifies the meaning as well.
