“Allah looks down on the night of the middle of Sha’ban and forgives all His creation, apart from the idolater and the Mushahin.”

Another chain from Abu Musa, from the Prophet (ﷺ) with similar wording.
Sunan Ibn Majah Book 5, Hadith 588
← Previous Hadith “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.’”

Sunan Ibn Majah Book 5, Hadith 587 Next Hadith → It was narrated from ‘Abdullah bin Abu Awfa that the Messenger of Allah (ﷺ) prayed two Rak’ah on the day when he was given the glad tidings of the head (death) of Abu Jahl.

Sunan Ibn Majah Book 5, Hadith 589