On the authority of Abu Hurairah that the Prophet said:

"Whosoever removes a worldly grief from a believer, Allah will remove from him one of the griefs of the Day of Judgment. Whosoever alleviates [the lot of] a needy person, Allah will alleviate [his lot] in this world and the next. Whosoever shields a Muslim, Allah will shield him in this world and the next. Allah will aid a servant [of His] so long as the servant aids his brother. Whosoever follows a path to seek knowledge therein, Allah will make easy for him a path to Paradise. No people gather together in one of the houses of Allah, reciting the Book of Allah and studying it among themselves, without tranquility descending upon them, mercy enveloping them, the angels surrounding them, and Allah making mention of them amongst those who are with Him. Whosoever is slowed down by his actions will not be hastened forward by his lineage."

Related by Muslim in these words.