Musnad Ahmad 437:1

Muhammad ibn Bakr narrated to us, Ibn Jurayj informed us, from Ibn al-Munkadir, from Abu Ayyub, from Maslamah ibn Mukhallad, that the Prophet, peace and blessings of Allah be upon him, said: "Whoever conceals a Muslim in the world, Allah the Almighty and Majestic will conceal him in the world and the Hereafter. Whoever saves a distressed person, Allah will relieve him of a distress from the distresses of the Day of Resurrection. And whoever is in the need of his brother, Allah the Almighty and Majestic will be in his need."