Below is a well-published Sermon of the Messenger of Allah (صلي الله عليه وسلم) on Ramadan; if anyone knows the source, please post it in a comment–it’s well-known as far as the internet goes!
“Indeed ahead of you is the blessed month of Allah. A month of blessing, mercy and forgiveness. A month which, with Allah, is the best of months. Its days, the best of days, its nights, the best of nights, and its hours, the best of hours. It is the month, which invites you to be the guests of Allah and invites you to be one of those near to Him. Each breath you take glorifies Him; your sleep is worship, your deeds are accepted and your supplications are answered. So, ask Allah, your Lord; to give you a sound body and an enlightened heart so you may be able to fast and recite His Book, for only he is unhappy who is devoid of Allah’s forgiveness during this great month.
“Remember the hunger and thirst of the Day of Qiyamah (Judgment) with your hunger and thirst; give alms to the needy and poor, honor your old, show kindness to the young ones, maintain relations with your blood relations; guard your tongues, close your eyes to that which is not permissible for your sight, close your ears to that which is forbidden to hear, show compassion to the orphans of people so compassion may be shown to your orphans. Repent to Allah for your sins and raise your hands in du’a during these times, for they are the best of times and Allah looks towards his creatures with kindness, Replying to them during the hours and granting their needs if He is asked…
“O People! Indeed your souls are dependent on your deeds, free it with istighfar (repentance) lighten its loads by long prostrations (sujood); and know that Allah swears by his might: That there is no punishment for the one who prays and prostrates and he shall have no fear of the Fire on the day when man stands before the Lord of the Worlds.
“O People! One who gives iftaar to a fasting person during this month will be like one who has freed someone and his past sins will be forgiven.”
Some of the people who were there then asked the Prophet (صلي الله عليه وسلم): “Not all of us are able to invite those who are fasting?” The Prophet (صلي الله عليه وسلم) replied: “Allah gives this reward even if the iftaar (meal) is a drink of water.”
He (صلي الله عليه وسلم) continues, “one who has good morals (akhlaaq) during this month will be able to pass the Siraat (hair-thin bridge over the Hellfire which every individual must cross on the Day of Judgment) … on the day that feet will slip … One who covers the faults of others will benefit in that Allah will curb His anger on the Day of Judgment.
“As for one who honors an orphan; Allah will honor him on the Day of Judgment. And for the one who spreads his kindness, Allah will spread His mercy over him on the day of Judgment.
“As for the one who cuts the ties of relation; Allah will cut His mercy from him.
“Whoever performs a recommended prayer in this month Allah will keep the fire of Hell away from him. Whoever performs an obligatory prayer, Allah will reward him with seventy prayers [worth] in this month.
“And whoever prays a lot during this month will have his load lightened on the day of measure. He who recites one verse of the Holy Qur’an will be given the rewards of reciting the whole Qur’an during other months.
“O People! Indeed during this month the doors of Heaven are open, therefore ask Allah not to close them for you; the doors of Hell are closed, so ask Allah to keep them closed for you. During this month Shaytaan is imprisoned, so ask your Lord not to let him have power over you.”
“The Prophet’s Sermon About Ramadan.” In the Name of Allah,the Most Beneficent, the Most Merciful. 22 Nov. 2001. 13 Sept. 2007 <http://www.iit.edu/~syednoo/ramadansermon.htm>.