Musnad Ahmad 30:309

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, and Ibn Numayr said: Al-A'mash informed us, from Abu Salih, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever relieves a believer of a distress from the distresses of the world, Allah will relieve him of a distress from the distresses of the Day of Resurrection. Whoever conceals a Muslim, Allah will conceal him in the world and the Hereafter. Whoever makes it easy for one in hardship, Allah will make it easy for him in the world and the Hereafter. Allah is in the aid of the servant as long as the servant is in the aid of his brother. Whoever treads a path seeking knowledge therein, Allah will make easy for him a path to Paradise by it. No people gather in a house from the houses of Allah, reciting the Book of Allah and studying it among themselves, except that tranquility descends upon them, mercy covers them, the angels surround them, and Allah, the Mighty and Majestic, mentions them among those who are with Him. And whoever is slowed down by his deeds, his lineage will not speed him up."