Well, the Hijri date 26 Rabi Al Thani 1223 corresponds to the Gregorian date Monday, 20 June 1808. This date lies in the fourth month of the Hijri year 1223 AH, which is Rabi Al-Thani of 1223 AH. Both this Hijri and Gregorian date occur on the single day that is Monday without any doubt. The Arabic date 1223/04/26 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 20 June 1808 to its equivalent Arabic date.
The following is the conversion of the Arabic date 26 Rabi Al Thani 1223 AH to its equivalent Gregorian date.
فَإِن تَوَلَّوْا۟ فَقَدْ أَبْلَغْتُكُم مَّآ أُرْسِلْتُ بِهِۦٓ إِلَيْكُمْ ۚ وَيَسْتَخْلِفُ رَبِّى قَوْمًا غَيْرَكُمْ وَلَا تَضُرُّونَهُۥ شَيْـًٔا ۚ إِنَّ رَبِّى عَلَىٰ كُلِّ شَىْءٍ حَفِيظٌۭ
And if ye turn away, still I have conveyed unto you that wherewith I was sent unto you, and my Lord will set in place of you a folk other than you. Ye cannot injure Him at all. Lo! my Lord is Guardian over all things.
Surah Hud(11:57)