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Here you go guys, the original-language page. The phrase the OP is talking about goes:
握りしめたその手を離さない...!
nigirishimeta sono te o hanasanai...!
Literally it says, "Grasped that hand do not let go of...!"
Grasped is in the past-tense.
Anyways, it doesn't look like
anybody is saying it, so Hinata is not declaring anything. It seems to me that it's instead coming from the omnipotent voice that lives in comics. Such voices are the ones who say things like, "Meanwhile, in Gotham City..." or "What will our heroes do now!" It's the final page of the chapter and in Naruto you will always hear the omnipotent voice pipe up on the last page. That's it.
Perhaps this omnipotent voice is imploring, as if saying to Hinata, "You've reached your goal! Now do not falter!" or something along those lines, if such phrases or metaphors can even be applied in the same way across cultures or languages, that was my
Western interpretation of how holding onto something can be a metaphor. I have no clue whether Japanese have such analogies about grabbing onto things.
Or it could be to Naruto. I like this one better ----> It has to do with Naruto choosing not to side with Obito and taking the hand of his friend instead. It's like the voice is telling him to hold tightly onto his friends and never let them be erased.