Musnad Ahmad 1899

It was narrated that Ibn "Abbas said: The Messenger of Allah (ﷺ) drew back the curtain and the people were lined up in rows behind Abu Bakr. He said: "O people, there is nothing left of the glad tidings of Prophethood except a good dream that a Muslim sees or that is seen for him. But I have been forbidden to recite the Qur"an when bowing or prostrating. As for bowing glorify your Lord therein, and as for prostrating, strive in du"a", for it is more likely to receive a response (from your Lord).”