Al-Baqarah · 2:189

189. They ask you, O Messenger, about the formation of the new moons and their changing states. Tell them in reply about the wisdom behind them: that they measure time for people, so that they know when to do their acts of worship, such as the months of Hajj and fasting, and the completion of the year for Zakat; they also fix the time frames of transactions, such as the deadlines for paying blood money or debts. It is not righteousness or goodness that you come to houses from the rear wearing your iḥrām for Hajj or Umrah, as they used to claim during the time of ignorance before Islam. Rather, true righteousness is the righteousness of whoever is mindful, outwardly and inwardly. So, enter houses from their correct doors, because it is easier for you and less troublesome. Allah does not overburden you with difficulty, so protect yourself from the punishment of Allah by doing good, in order that you may be successful in achieving what you wish for, and in escaping from what you fear.