Well, the Hijri date 21 Jumada Al Akhira 1366 corresponds to the Gregorian date Monday, 12 May 1947. This date lies in the sixth month of the Hijri year 1366 AH, which is Jumada Al-Thani of 1366 AH. Both this Hijri and Gregorian date occur on the single day that is Monday without any doubt. The Arabic date 1366/06/21 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 May 1947 to its equivalent Arabic date.
The following is the conversion of the Arabic date 21 Jumada Al Akhira 1366 AH to its equivalent Gregorian date.
وَقَالُوا۟ مَا فِى بُطُونِ هَٰذِهِ ٱلْأَنْعَٰمِ خَالِصَةٌۭ لِّذُكُورِنَا وَمُحَرَّمٌ عَلَىٰٓ أَزْوَٰجِنَا ۖ وَإِن يَكُن مَّيْتَةًۭ فَهُمْ فِيهِ شُرَكَآءُ ۚ سَيَجْزِيهِمْ وَصْفَهُمْ ۚ إِنَّهُۥ حَكِيمٌ عَلِيمٌۭ
And they say: That which is in the bellies of such cattle is reserved for our males and is forbidden to our wives; but if it be born dead, then they (all) may be partakers thereof. He will reward them for their attribution (of such ordinances unto Him). Lo, He is Wise, Aware.
Surah Al-An'aam(6:139)
Sahih al-Bukhari
Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh))
"And why did you not, when you heard it, say: It is not right for us to speak of this..." (V.24:16)
Narrated Al-Qasim:
Ibn `Abbas asked `Aisha's permission to enter. Al-Qasim then narrated the whole Hadith (as in 277) but did not mention: "Would that I had been forgotten and out of sight."
Sahih al-Bukhari 4754