"Narrated by 'Abdullah bin Umar: Allah's Apostle said, "A Muslim is a brother of another Muslim, so he should not oppress him, nor should he hand him over to an oppressor. Whoever fulfilled the needs of his brother, Allah will fulfill his needs; whoever brought his (Muslim) brother out of a discomfort, Allah will bring him out of the discomforts of the Day of Resurrection, and whoever screened a Muslim, Allah will screen him on the Day of Resurrection"
Respect the house of Allah (SWT).
Keep your voice down.
Refrain from trading and selling in the Mosque.
Keep your place clean.
Assist your fellow prayer when in need.
Refrain from smoking inside or outside within the perimeter of the Mosque.