Musnad Ahmad 3798

It was narrated from Ibn Mas'ood (رضي الله عنه) that The Messenger of Allah (ﷺ) said: "When the last third of the night comes, Allah, may He he glorified and exalted, descends to the lowest heaven, then He opens the gate of heaven, then He stretches forth His Hand and says: "Is there anyone who is asking, so that he may be given what he asked for?' And He remains like that until dawn breaks."