Surah Al-Baqara (2) — Ayah 189

(Ayah 189) ➊ {الْاَهِلَّةِ :} is the plural of { ”هِلاَلٌ“ }. The crescent moon is called "hilal" on the first and second nights, then it is called "qamar." (Raghib) When people inquired about the wisdom behind the waxing and waning of the moon, Allah Almighty replied that the moon appears every month in the form of a crescent, then on the fourteenth night it becomes full (badr). In the last night, it completely disappears, then reappears as a new crescent, by which not only the people of cities and towns but also those living in deserts and seas can know that a new month has begun, and from its various phases, they can also determine the date. Whereas the sun always remains complete, it was not possible for people living in every part of the world to determine time and date by it, so Allah Almighty appointed the changing moons as a calendar. Hajj, expiations, and matters such as divorce and the waiting period after death have been prescribed according to the moon. In view of the moons that rise every month, the plural form { ”الْاَهِلَّةِ“ } has been mentioned.
➋ {وَ لَيْسَ الْبِرُّ بِاَنْ تَاْتُوا الْبُيُوْتَ مِنْ ظُهُوْرِهَا …:} When Hajj was mentioned, a custom of ignorance during the days of Hajj was refuted. Bara’ (may Allah be pleased with him) says that this verse was revealed about us. When the Ansar performed Hajj and then returned, they would not enter their houses from the doors. Now, when a man from the Ansar (returned from Hajj) and entered from his door, it was as if he was reproached for it, so this verse was revealed: « وَ لَيْسَ الْبِرُّ بِاَنْ تَاْتُوا الْبُيُوْتَ مِنْ ظُهُوْرِهَا وَ لٰكِنَّ الْبِرَّ مَنِ اتَّقٰى وَ اْتُوا الْبُيُوْتَ مِنْ اَبْوَابِهَا» [ بخاری، العمرۃ، باب قول اللہ تعالٰی : « و أتوا البیوت من أبوابہا » : ۱۸۰۳ ]
In another narration, Bara’ bin Azib (may Allah be pleased with them both) says that in the time of ignorance, when people put on ihram, they would enter their houses from the back, so this verse was revealed. [ بخاری، التفسیر، بابٌ : «ولیس البر بأن تأتوا البیوت … » : ۴۵۱۲ ] The verse refutes both.
➌ {”وَ لَيْسَ الْبِرُّ بِاَنْ“} In this, due to the emphasis of { ”لَيْسَ“ } with "ba," it has been translated as "Righteousness is by no means this."

189. 1. In the era of ignorance, when the Ansar would enter into the state of Ihram for Hajj or Umrah and then needed to come home for some particular necessity, instead of coming through the door, they would climb over the wall from behind to enter, considering this to be a virtue. Allah Almighty said that this is not a virtue.

189. They ask you about the new moons [248]. Say, "They are measurements of time for the people and for Hajj." And it is not righteousness that you enter houses from their backs [249], but righteousness is in one who fears Allah. So enter houses through their doors and fear Allah so that you may succeed.

[248]
The Lunar Calendar is the Natural Calendar:

The original question of the inquirer was how the moon waxes and wanes and why its phases keep changing. However, this question is a complex issue of astronomy, which is above the intellectual level of the common person, and above all, it has no relation to the practical life and guidance of man. Therefore, Allah Almighty turned the answer to this question towards that which is related to human guidance and practical life, and said that this is a natural calendar for you. Also, you can determine the times of Hajj from these lunar phases. Here, it should be kept in mind that the Shariah rulings related to the times of the day are connected to the sun, such as the times of prayers and the times of suhoor and iftar for fasting. Similarly, the counting of days is related to the sun. But when the period is a month or more than a month, the counting of the period will be according to the moon. For example, the days of Ramadan (whether they are twenty-nine or thirty), the waiting period (‘iddah) of a widow or a divorced woman, the period of pregnancy, breastfeeding, etc., and the calculation of zakat will also be according to the lunar year. From this, it is also understood that the real and natural calendar is the lunar one, and this is the meaning of "mawaqeet linnas" (appointed times for mankind). As for the times of Hajj, they are the months of Shawwal, Dhu al-Qa'dah, and the first ten days of Dhu al-Hijjah.

[249]
The Presumed Good Deeds in the Age of Ignorance:

One of the customs of the Age of Ignorance was that after donning the ihram for Hajj, if someone needed to return home, and similarly after returning from Hajj, these people would enter the house not from the front door but from the back or through a hole in the back wall, and they considered this a virtuous act. Thus, Hazrat Bara’ ؓ says that this verse was revealed concerning us, the Ansar. When they returned from Hajj, they would not enter through the doors but from the back. Once, an Ansari entered through the door, so everyone started cursing and blaming him. Then this verse was revealed. [بخاري، كتاب المناسك، باب قوله تعالىٰ واٰتوا البيوت من ابوابها] From this, it is incidentally understood that considering something a virtue and introducing it into the religion is blameworthy and forbidden, and innovations (bid‘ah) also fall under this category.