Salim reported on the authority of his father (Radiyallaahu `anhum) that Allah’s Messenger (Sallallaahu `alayhi wa sallam) said:

“A Muslim is the brother of a fellow-Muslim. He should neither commit oppression upon him nor ruin him, and he who meets the need of a brother, Allah would meet big needs, and he who relieved a Muslim from hardship Allah would relieve him from the hardships to which he would be put on the Day of Resurrection, and he who did not expose (the follies of a Muslim) Allah would conceal his follies on the Day of Resurrection.”

Sahih Muslim (Book 032, Number 6250)