This Saturday the 31st of March, it will be the 12th of Rabi' al-Awwal, the day that Muslims celebrate the birth of God's Messenger Muhammad, peace and blessings be upon him as many times as people have celebrated his message! The celebration is called the Mewlid, from the arabic word for birth.
There are those who have no proper understanding of the Sunna that argue that celebrating the Prophet's birthday is an innovation. Is it wrong to celebrate the coming of the best of mankind, the bearer of God's Final Message to humanity? Are we not really celebrating the Message itself?
Anyway, these people read the Qur'an and read the Hadith but they don't understand it. If they truly understood it they would see that the Prophet (pbuh) celebrated his birthday every single week, let alone every year!
For we know that the Prophet (pbuh) enjoined Muslims to fast every Monday and Thursday. The sayyida Aisha said, "The Messenger of Allah (PBUH) used to observe fast on Mondays and Thursdays." [Reported by Tirmidhi]
When asked why he, peace be upon him, fasted and enjoined others to fast on Monday he said it is because that is the day he was born:
"The Messenger of Allah (PBUH) was asked about fasting on Mondays. He said, 'That is the day on which I was born and the day on which I received Revelation.' " [Reported in Sahih Muslim].
We are also told in Sahih Bukhari that when the Prophet was born (and it happened to be on a Monday) the Prophet's uncle Abu Lahab was so pleased at the birth of his nephew that he freed the slave-girl Thuwaiba when she brought him the news. Because of this, his punishment in the grave (for later becoming an enemy of the Prophet and of Islam) is reduced every Monday.
Based on this hadith in Bukhari, the scholar Shams al-Din al-Dimashqi wrote,
If an unbeliever, condemned by the Quran to eternal pain,
Can be relieved every Monday through his joy at Ahmad,
Then what must a true servant of God hope to gain,
When with the truth of Tawhid he felt joy at Ahmad?
Don't forget to do extra salawaat on the Prophet on that day! Happy Mewlid!