It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "A Muslim is the brother of a Muslim; he does not wrong him, nor does he abandon him helpless. Whoever is engaged in fulfilling his brother's need, Allah is engaged in fulfilling his need; whoever relieves a Muslim of a hardship of this world, Allah will thereby relieve him of one of the hardships of the Day of Resurrection; and whoever conceals (the faults of) a Muslim, Allah will conceal him on the Day of Resurrection."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13081