Well, the Hijri date 15 Rajab 1391 corresponds to the Gregorian date Saturday, 4 September 1971. This date lies in the seventh month of the Hijri year 1391 AH, which is Rajab of 1391 AH. Both this Hijri and Gregorian date occur on the single day that is Saturday without any doubt. The Arabic date 1391/07/15 is calculated using the Umm Al-Qura calendar and the sighting of the moon. One thing to remember is that this Arabic date may occur on different Gregorian date depending upon the region and country and obviously the moon.
If you are still not sure about the date then you can use our Arabic date converter.
The following is the conversion of the Gregorian date 4 September 1971 to its equivalent Arabic date.
The following is the conversion of the Arabic date 15 Rajab 1391 AH to its equivalent Gregorian date.
وَإِن تُطِعْ أَكْثَرَ مَن فِى ٱلْأَرْضِ يُضِلُّوكَ عَن سَبِيلِ ٱللَّهِ ۚ إِن يَتَّبِعُونَ إِلَّا ٱلظَّنَّ وَإِنْ هُمْ إِلَّا يَخْرُصُونَ
If thou obeyedst most of those on earth they would mislead thee far from Allah's way. They follow naught but an opinion, and they do but guess.
Surah Al-An'aam(6:116)