Well, the Hijri date 20 Dhul Qidah 1278 corresponds to the Gregorian date Sunday, 18 May 1862. This date lies in the eleventh month of the Hijri year 1278 AH, which is Dhu Al-Qidah of 1278 AH. Both this Hijri and Gregorian date occur on the single day that is Sunday without any doubt. The Arabic date 1278/11/20 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 18 May 1862 to its equivalent Arabic date.
The following is the conversion of the Arabic date 20 Dhul Qidah 1278 AH to its equivalent Gregorian date.
۞ يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ كُونُوا۟ قَوَّٰمِينَ بِٱلْقِسْطِ شُهَدَآءَ لِلَّهِ وَلَوْ عَلَىٰٓ أَنفُسِكُمْ أَوِ ٱلْوَٰلِدَيْنِ وَٱلْأَقْرَبِينَ ۚ إِن يَكُنْ غَنِيًّا أَوْ فَقِيرًۭا فَٱللَّهُ أَوْلَىٰ بِهِمَا ۖ فَلَا تَتَّبِعُوا۟ ٱلْهَوَىٰٓ أَن تَعْدِلُوا۟ ۚ وَإِن تَلْوُۥٓا۟ أَوْ تُعْرِضُوا۟ فَإِنَّ ٱللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًۭا
O ye who believe! Be ye staunch in justice, witnesses for Allah, even though it be against yourselves or (your) parents or (your) kindred, whether (the case be of) a rich man or a poor man, for Allah is nearer unto both (them ye are). So follow not passion lest ye lapse (from truth) and if ye lapse or fall away, then lo! Allah is ever Informed of what ye do.
Surah An-Nisaa(4:135)