The month of Ramadan may consist of twenty-nine days. So do not fast till you have sighted it (the new moon) and do not break fast, till you have sighted it (the new moon of Shawwal), and if the sky is cloudy for you, then calculate. (Using translation from Muslim 1080e)  

قَالَ رَسُولُ اللَّهِ ﷺ «إِنَّمَا الشَّهْرُ تِسْعٌ وَعِشْرُونَ فَلَا تَصُومُوا حَتَّى تَرَوْهُ وَلَا تُفْطِرُوا حَتَّى تَرَوْهُ فَإِنْ غُمَّ عَلَيْكُمْ فَاقْدُرُوا لَهُ»  

[Machine] "O people, you have indeed achieved goodness—or a reward—and we are gathering. So whoever wants to join us in the gathering, let them join. And whoever wishes to return to their family, let them return."  

"يَا أَيُّهَا النَّاسُ: إِنَّكُمْ قَدْ أَصبْتُمْ خَيْرًا -أَوْ أَجْرًا- وَإنَّا مُجَمِّعُونَ، فَمَنْ أَرَادَ أنْ يُجَمَعِّ مَعَنَا فَلْيُجَمِّعْ، وَمَنْ أرَادَ أَنَّ يَرْجع إِلى أَهْلِهِ فَليَرجعْ".  

"There are five nights wherein supplications are not rejected: (1) the first night of ˹the month of˺ Rajab, (2) the night of the middle of ˹the month of˺ Shaʿbān, (3) the night of ˹every˺ Friday, (4) the night of the ˹ʿīd of˺ Fiṭr, and (5) the night of the ˹ʿīd of˺ Sacrifice.  

«خَمْسُ لَيَالٍ لا تُرد فيهن الدَّعْوةُ: (١) أَوَّلُ لَيْلَةٍ مِن رجبٍ، (٢) ولَيْلَة النِّصْفِ مِنْ شَعْبَانَ، (٣) ولَيلَةِ الجُمُعةِ، (٤) ولَيْلَةِ الفِطر، (٥) ولَيْلَةِ النَّحْرِ۔»  

Allah ordains goodness during four nights: (1) the night of ˹the ʿĪd of˺ Adḥá and (2) ˹the ʿĪd of˺ Fiṭr, (3) the night of the middle of Shaʿbān – where the lifespans and provisions are ordained and the ˹upcoming performance˺ of Ḥajj is ordained – and (4) the night of ʿArafah until the Ādhān.  

«يَنْسَخُ اللَّه ﷻ الخَيْرَ فِى أَرْبَعِ لَيَالٍ نَسخًا: (١) ليلةِ الأضحى، (٢) والفطر، (٣) وليلةِ النصفِ مِنْ شعبَانَ يَنْسخُ فِيهَا الآجال والأرْزَاق ويُكْتَبُ فِيهَا الحَجُّ، (٤) وفِى ليْلةِ عرفَةَ إِلى الأذَانِ۔»