It was narrated that ‘Aishah said:

“I missed the Prophet (ﷺ) one night, so I went out looking for him. I found him at Al-Baqi’, raising his head towards the sky. He said: ‘O ‘Aishah, were you afraid that Allah and His Messenger would wrong you?’” She said: “I said: ‘No, it is not that, but I thought that you had gone to one of your other wives.’ He said: ‘Allah descends on the night of the middle of Sha’ban to the lowest heaven, and He forgives more than the numbers of hairs on the sheep of Banu Kalb.’”

حَدَّثَنَا عَبْدَةُ بْنُ عَبْدِ اللَّهِ الْخُزَاعِيُّ، وَمُحَمَّدُ بْنُ عَبْدِ الْمَلِكِ أَبُو بَكْرٍ، قَالاَ حَدَّثَنَا يَزِيدُ بْنُ هَارُونَ، أَنْبَأَنَا حَجَّاجٌ، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، قَالَتْ فَقَدْتُ النَّبِيَّ ـ صلى الله عليه وسلم ـ ذَاتَ لَيْلَةٍ فَخَرَجْتُ أَطْلُبُهُ فَإِذَا هُوَ بِالْبَقِيعِ رَافِعٌ رَأْسَهُ إِلَى السَّمَاءِ فَقَالَ ‏"‏ يَا عَائِشَةُ أَكُنْتِ تَخَافِينَ أَنْ يَحِيفَ اللَّهُ عَلَيْكِ وَرَسُولُهُ ‏"‏ ‏.‏ قَالَتْ قَدْ قُلْتُ وَمَا بِي ذَلِكَ وَلَكِنِّي ظَنَنْتُ أَنَّكَ أَتَيْتَ بَعْضَ نِسَائِكَ ‏.‏ فَقَالَ ‏"‏ إِنَّ اللَّهَ تَعَالَى يَنْزِلُ لَيْلَةَ النِّصْفِ مِنْ شَعْبَانَ إِلَى السَّمَاءِ الدُّنْيَا فَيَغْفِرُ لأَكْثَرَ مِنْ عَدَدِ شَعَرِ غَنَمِ كَلْبٍ ‏"‏ ‏.‏