Jabir ibn 'Abdullah · The Book On The Mosques And The Congregations

"One of my paternal uncles made some food for the Prophet and said to the Prophet: 'I would like you to eat and perform prayer in my house.' So he went to him, and in his house there was one of these Fahl. He ordered that a corner be swept and water sprinkled in it, then he performed prayer and we prayed with him.'" (Sahih)Abu 'Abdullah bin Majah said: A Fahl is a mat that has become black (through use).

He heard Abu Hurairah say: "I heard the Messenger of Allah say: 'Whoever hears a man making a lost-and-found announcement in the mosque, let him say: "May Allah not return it to you!" For the mosques were not built for that.'"

"Banu Salimah wanted to move from their homes to somewhere near the mosque, but the Prophet did not want the outskirts of Al-madinah to be left vacant, so he said: 'O Banu Salimah, do you not hope for the reward of your footsteps?' So they stayed (where they were)."

The Prophet said: "Whoever hears the call and does not come, his prayer is not valid, except for those who have an excuse."