Well, the Hijri date 13 Rabi Al Thani 1231 corresponds to the Gregorian date Tuesday, 12 March 1816. This date lies in the fourth month of the Hijri year 1231 AH, which is Rabi Al-Thani of 1231 AH. Both this Hijri and Gregorian date occur on the single day that is Tuesday without any doubt. The Arabic date 1231/04/13 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 12 March 1816 to its equivalent Arabic date.
The following is the conversion of the Arabic date 13 Rabi Al Thani 1231 AH to its equivalent Gregorian date.
وَلَن يَتَمَنَّوْهُ أَبَدًۢا بِمَا قَدَّمَتْ أَيْدِيهِمْ ۗ وَٱللَّهُ عَلِيمٌۢ بِٱلظَّٰلِمِينَ
But they will never long for it, because of that which their own hands have sent before them. Allah is aware of evil-doers.
Surah Al-Baqara(2:95)