Qur'an 2:189

۞ يَسْـَٔلُونَكَ عَنِ ٱلْأَهِلَّةِ ۖ قُلْ هِىَ مَوَٰقِيتُ لِلنَّاسِ وَٱلْحَجِّ ۗ وَلَيْسَ ٱلْبِرُّ بِأَن تَأْتُوا۟ ٱلْبُيُوتَ مِن ظُهُورِهَا وَلَـٰكِنَّ ٱلْبِرَّ مَنِ ٱتَّقَىٰ ۗ وَأْتُوا۟ ٱلْبُيُوتَ مِنْ أَبْوَٰبِهَا ۚ وَٱتَّقُوا۟ ٱللَّهَ لَعَلَّكُمْ تُفْلِحُونَ

“They ask you, [O Muḥammad], about the crescent moons. Say, "They are measurements of time for the people and for ḥajj [pilgrimage]." And it is not righteousness to enter houses from the back, but righteousness is [in] one who fears Allāh. And enter houses from their doors. And fear Allāh that you may succeed.”

Al-Baqara 2:189 · Saheeh International