“Our Lord, the Blessed and Exalted, descends when one third of
the
night remains, every night and He says: ‘Who will ask of Me, that
I
may give him? Who will call upon Me, that I may answer him? Who will
ask My forgiveness, that I may forgive him?’ until dawn comes.”
Hence
they used to prefer voluntary prayers at the end of the night
rather
than at the beginning.
Sunan Ibn Majah Book 5, Hadith 564