Salmaan Al-Faarisi, may Allaah be pleased with him, reported that the Prophet sallallaahu 'alaihi wa sallam gave a speech on the last day of Sha’baan, and said, "O people! You are being approached by a great and blessed month. A month which contains a night that is better than one thousand months. Allaah made fasting within it an obligation and made praying in that night an optional act of worship. He who performs any righteous voluntary act within it, will be rewarded like one who does an obligatory act at any time other than during Ramadhaan.
"He who performs an obligatory act of worship within it will be rewarded like he who performs seventy acts of worship at any time outside this month. It is the month of perseverance - and perseverance is rewarded with Jannah (Paradise). It is the month of compassion, in which the sustenance of a believer increases. He who feeds a fasting person within this month has his sins forgiven and he will be protected and released from the hellfire. He also gets the reward of that person's fasting without decreasing the reward of the fasting person."
Then the companions, may Allaah be pleased with them, said, ‘O messenger of Allaah! Not all of us can find the extra food needed to feed another fasting person’.
So the Prophet sallallaahu 'alaihi wa sallam responded, "Allaah will give you the reward of feeding a fasting person even if you were to give him just a sip of milk, a date, or a sip of water. He who feeds a fasting person until he is full, Allaah will make him drink out of my river, a sip of which will never allow him to be thirsty until he enters Jannah."