The Messenger of Allah ﷺ said, "Whoever relieves a believer of one of the hardships of this world, Allah will relieve him of one of the hardships of the Day of Resurrection. And whoever eases the burden of one in difficulty, Allah will ease his burden in this world and the next."
قال رسول الله ﷺ: من نفس عن مؤمن كربة من كرب الدنيا نفس الله عنه كربة من كرب يوم القيامة، ومن يسر على معسر يسر الله عليه في الدنيا والآخرة.
Muslim narrated it in the Book of Knowledge (2699) through various routes from Abu Muawiya, from Amash, from Abu Salih, from Abu Hurairah, within a longer hadith mentioned in its proper place.