One night Allah's Messenger (ﷺ) offered the prayer in the Mosque and the people followed him. The next
night he also offered the prayer and too many people gathered. On the third and the fourth nights more
people gathered, but Allah's Messenger (ﷺ) did not come out to them. In the morning he said, "I saw what
you were doing and nothing but the fear that it (i.e. the prayer) might be enjoined on you, stopped me
from coming to you." And that happened in the month of Ramadan.
Sahih al-Bukhari Book 19, Hadith 9