Ayesha reported,
I lost track of the Messenger of Allah ﷺ one night, so I went out and found him at al-Baqi. He said, "Were you afraid that Allah and His Messenger would wrong you?"I replied, "Messenger of Allah, I thought you had gone to one of your other wives."He said, "Allah 
descends on the night of mid-Shaban to the lowest heaven and forgives more people than the number of hairs on the sheep of the tribe of Kalb."
Tirmidhi 739
Daifحدثنا أحمد بن منيع حدثنا يزيد بن هارون أخبرنا الحجاج بن أرطاة عن يحيى بن أبي كثير عن عروة
عن عائشة قالت
فقدت رسول الله ﷺ ليلة فخرجت فإذا هو بالبقيع فقال أكنت تخافين أن يحيف الله عليك ورسوله قلت يا رسول الله إني ظننت أنك أتيت بعض نسائك فقال إن الله عز وجل ينزل ليلة النصف من شعبان إلى السماء الدنيا فيغفر لأكثر من عدد شعر غنم كلب
[Its chain of transmission is daif] Ibn Majah also narrated it, in Establishing the Prayers, the chapter on what has been said about the night of the middle of Shaban, hadith no. 1389, from the hadith of Yazid bin Harun, with the same chain.Hajjaj bin Artah is daif and a mudallis, and his hadith has weak corroborating narrations. On this subject there is also a report from Abu Bakr Siddiq [Ibn Adi in Al-Kamil 5/1946, Ibn Jawzi in Al-Wahiyat 2/66-67, and Ibn Abu Asim in Al-Sunnah, p. 222].