Hadith 35, 40 Hadith Qudsi
On the authority of Abu Hurayrah (may Allah be pleased with him), who said that the Messenger of Allah (ﷺ) said:
Our Lord (glorified and exalted be He) descends each night to the earth's sky when there remains the final third of the night, and He says: Who is saying a prayer to Me that I may answer it? Who is asking something of Me that I may give it him? Who is asking forgiveness of Me that I may forgive him?

It was related by al-Bukhari (also by Muslim, Malik, at-Tirmidhi and Abu Dawud). In a version by Muslim the Hadith ends with the words: And thus He continues till [the light of] dawn shines.
عَنْ أَبي هُرَيْرَةَ رَضِيَ اللهُ عَنْهُ  أَنَّ رَسُولَ اللهِ  صَلَّى الله عَلَيْهِ وَ سَلَّمَ قَالَ 
   
يَتنزَّلُ رَبُّنَا ، تَبَارَكَ وَتَعَالَى ، كُلَّ لَيْلَةٍ إلي سَمَاءِ الدُّنْيا ، حينَ يَبْقَى ثُلُثُ اللَّيْلِ الاخِرُ ، فَيَقُولُ  مَنْ يَدْعُوني فأَسْتَجِيبَ لَه ؟ مَنْ يَسْأَلُني فَأُعْطِيَهُ ؟ مَنْ يَسْتَغْفِرُني فَأَغْفِرَلَهُ ؟ 
     
 رواه البخاري (وكذلك مسلم ومالك والترمذي و أبو داود) 
وفي رواية لمسلم زيادة: 
فَلا يَزالُ كذَلِك حَتَى يُضِيءَ الفَجْرُ