Well, the Hijri date 18 Muharram 1491 corresponds to the Gregorian date Thursday, 22 March 2068. This date lies in the first month of the Hijri year 1491 AH, which is Muharram of 1491 AH. Both this Hijri and Gregorian date occur on the single day that is Thursday without any doubt. The Arabic date 1491/01/18 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 22 March 2068 to its equivalent Arabic date.
The following is the conversion of the Arabic date 18 Muharram 1491 AH to its equivalent Gregorian date.
أَوْ تَقُولُوا۟ لَوْ أَنَّآ أُنزِلَ عَلَيْنَا ٱلْكِتَٰبُ لَكُنَّآ أَهْدَىٰ مِنْهُمْ ۚ فَقَدْ جَآءَكُم بَيِّنَةٌۭ مِّن رَّبِّكُمْ وَهُدًۭى وَرَحْمَةٌۭ ۚ فَمَنْ أَظْلَمُ مِمَّن كَذَّبَ بِـَٔايَٰتِ ٱللَّهِ وَصَدَفَ عَنْهَا ۗ سَنَجْزِى ٱلَّذِينَ يَصْدِفُونَ عَنْ ءَايَٰتِنَا سُوٓءَ ٱلْعَذَابِ بِمَا كَانُوا۟ يَصْدِفُونَ
Or lest ye should say: If the Scripture had been revealed unto us, we surely had been better guided than are they. Now hath there come unto you a clear proof from your Lord, a guidance and mercy; and who doeth greater wrong than he who denieth the revelations of Allah, and turneth away from them? We award unto those who turn away from Our revelations an evil doom because of their aversion.
Surah Al-An'aam(6:157)