The Messenger of Allah ﷺ drew back the curtain while the people were standing in rows behind Abu Bakr. He said, "People, nothing remains of the glad tidings of prophethood except the righteous dream that a Muslim sees, or that is seen for him. I have been forbidden to recite the Quran while bowing or prostrating. As for bowing, magnify the Lord in it. As for prostration, strive earnestly in supplication, for it is most fitting that you be answered."
كشف رسول الله الستارة، والناس صفوف خلف أبي بكر فقال: أيها الناس إنه لم يبق من مبشرات النبوة إلا الرؤيا الصالحة يراها المسلم، أو ترى له، ألا وإني نهيت أن أقرأ القرآن راكعا أو ساجدا، فأما الركوع فعظموا فيه الرب عز وجل، وأما السجود فاجتهدوا في الدعاء، فقمن أن يستحاب لكم.
Muslim narrated it in "The Prayer" (479) via Sufyan bin Uyayna, "Sulayman bin Suhaym informed me, from Ibrahim bin Abdullah bin Mabad, from his father, from Ibn Abbas," and he mentioned it. The hadith was mentioned earlier in the chapter on the prohibition of reciting the Quran during ruku and sujud.