Abu Huraira reported Allah's Messenger (ﷺ) as saying
He who alleviates the suffering of a brother out of the sufferings of the world, Allah would alleviate his suffering from the sufferings of the Day of Resurrection, and he who finds relief for one who is hard-pressed, Allah would make things easy for him in the Hereafter, and he who conceals (the faults) of a Muslim, Allah would conceal his faults in the world and in the Hereafter. Allah is at the back of a servant so long as the servant is at the back of his brother, and he who treads the path in search of knowledge, Allah would make that path easy, leading to Paradise for him and those persons who assemble in the house among the houses of Allah (mosques) and recite the Book of Allah and they learn and teach the Qur'an (among themselves) there would descend upon them tranquility and mercy would cover them and the angels would surround them and Allah mentions them in the presence of those near Him, and he who is slow-paced in doing good deeds, his (high) lineage does not make him go ahead.
This hadith has been narrated on the authority of Abu Huraira through another chain of transmitters but with a slight variation of wording.
Agharr Abi Muslim reported
I bear witness to the fact that both Abu Huraira and Abu Sa'id Khudri were present when Allah's Messenger may peace be upon him) said : The people do not sit but they are surrounded by angels and covered by Mercy , and there descends upon them tranquillity as they remember Allah , and Allah makes a mention of them to those who are near Him.
This hadith has been narrated on the authority of Shu'ba with the same chain of transmitters.
Abu Sa'id Khudri reported that Mu'awiya went to a circle in the mosque and said
What makes you sit here? They said: We are sitting here in order to remember Allah. He said: I adjure you by Allah (to tell me whether you are sitting here for this very purpose)? They said: By Allah, we are sitting here for this very purpose. Thereupon, he said: I have not demanded you to take an oath, because of any allegation against you and none of my rank in the eye of Allah's Messenger (ﷺ) is the narrator of so few ahadith as I am. The fact is that Allah's Messenger (ﷺ) went out to the circle of his Companions and said: What makes you sit? They said: We are sitting here in order to remember Allah and to praise Him for He guided us to the path of Islam and He conferred favours upon us. Thereupon he adjured by Allah and asked if that only was the purpose of their sitting there. They said: By Allah, we are not sitting here but for this very purpose, whereupon he (the Messenger) said: I am not asking you to take an oath because of any allegation against you but for the fact that Gabriel came to me and he informed me that Allah, the Exalted and Glorious, was talking to the angels about your magnificence.