Abdullah bin Umar reported,
The Messenger of Allah ﷺ said, "A Muslim is the brother of another Muslim. He does not wrong him, nor does he abandon him to his enemy. Whoever attends to the need of his brother, Allah 
will attend to his need. Whoever relieves a Muslim of a hardship, Allah will relieve him of one of the hardships of the Day of Resurrection. And whoever conceals the faults of a Muslim, Allah will conceal his faults on the Day of Resurrection."
Ahmad 5646
Sahihحدثنا حجاج حدثنا ليث حدثني عقيل عن ابن شهاب أن سالم بن عبد الله أخبره أن
عبد الله بن عمر أخبره
أن رسول الله ﷺ قال المسلم أخو المسلم لا يظلمه ولا يسلمه من كان في حاجة أخيه كان الله عز وجل في حاجته ومن فرج عن مسلم كربة فرج الله عز وجل عنه بها كربة من كرب يوم القيامة ومن ستر مسلما ستره الله يوم القيامة
Its isnad is sahih. Bukhari narrated it 70:5 from Yahya bin Bukayr, and Muslim narrated it 2:283 from Qutayba bin Saeed, both of them from Layth, that is Ibn Saad, with this isnad. Bukhari also narrated it in abbreviated form 12:288 from Yahya bin Bukayr from Layth, and Abu Dawud also narrated it, as mentioned in Targheeb wal-Tarheeb 3:250, see also 4749 and 5357. We have already referred, in the commentary on the latter of these two, to this hadith being reported by the two sheikhs.