The Prophet (ﷺ) had a mat which he used to spread during the day and use as a curtain at night. So a number of people gathered at night facing it and prayed behind him.
Sahih al-Bukhari Book 10, Hadith 124
← Previous Hadith Allah's Messenger (ﷺ) used to pray in his room at night. As the wall of the room was LOW, the people saw him and some of them stood up to follow him in the prayer. In the morning they spread the news. The following night the Prophet (ﷺ) stood for the prayer and the people followed him. This went on for two or three nights. Thereupon Allah's Messenger (ﷺ) did not stand for the prayer the following night, and did not come out. In the morning, the people asked him about it. He replied, that he way afraid that the night prayer might become compulsory.

Sahih al-Bukhari Book 10, Hadith 123 Next Hadith → Allah's Messenger (ﷺ) made a small room in the month of Ramadan (Sa`id said, "I think that Zaid bin Thabit said that it was made of a mat") and he prayed there for a few nights, and so some of his companions prayed behind him. When he came to know about it, he kept on sitting. In the morning, he went out to them and said, "I have seen and understood what you did. You should pray in your houses, for the best prayer of a person is that which he prays in his house except the compulsory prayers."

Sahih al-Bukhari Book 10, Hadith 125