Is it allowed to perform full صلاة(salat) instead of قصر (Qasr)?

We often perform صلاة القصر (salatul qasr) while travelling. But sometimes, while returning from the tour, it becomes confusing that am I still مسافر (musafir) or not. So, it seems to me to seek a better way to remain safe. If it is permissible to perform full صلاة(salat) when only قصر (Qasr) is فرض(farj) on me, then I could perform full صلاة(salat) to remain safe. Now, the question is very clear. Is it allowed to perform full صلاة(salat) instead of قصر (Qasr)? Note that, Simply yes/no is discouraged as it is not a discussion. Rather please, provide the evidence from القرآن الكريم (Quran) and الحديث(Hadis).