A scholar in our country said in his radio lecture that was listened to by millions of Muslims in our country that Prophet Muhammad (SAW) celebrated his birthday by fasting every Monday. It is not our intention to degrade this scholar, but we would simply like to clarify if this is true.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The Prophet Muhammad used to fast on Monday and he reasoned it by saying: "That is the day on which I was born and the day on which I received revelations." [Muslim]

He also clarified the reason of fasting – particularly Monday – in the following Hadeeth (narration) from Abu Hurayrah that the Prophet said: "The actions are presented (before Allaah) on every Monday and Thursday so, I like to have my deeds presented while I am fasting." This narration was reported by Imaam Ahmad and At-Tirmithi ; the latter grades this Hadeeth as Hasan.

Abu Hurayrah also said, "The Prophet of Allaah used to fast on Monday and Thursday. When was asked about it, he said: "The work of the servants (of Allaah) are presented (to Allaah) on every Monday and Thursday. Every Muslim or Mu'min is forgiven except for those who are boycotting each other. He Says (about them): "Leave them ." [Musnad Ahmad]

The Prophet explained in the above Hadeeth that Allaah The Almighty created him and bestowed favors upon him by choosing him as a Prophet on Monday, thus he wanted to be grateful to Allaah The Almighty for His blessings by fasting on that day.

Therefore, if the scholar as mentioned in your question means that the Prophet used to fast every Monday to be grateful to Allaah The Almighty, this meaning is correct and the Muslims are also recommended to fast on this day following the practice of the Prophet . However, keeping a fast particularly the twelfth of Rabee’uth-Thaani is not correct.

In fact, the Companions of Prophet Muhammad used to fast on the days Prophet Muhammad fasted and they would not consider those days feasts or celebrate them in anyway. It has not been reported that any of them claimed or tried to celebrate the birthday of the Prophet, sallallaahu ‘alayhi wa sallam, or the birthdays of Abu Bakr or ‘Umar . Indeed virtues are in following the righteous predecessors and vice lies in the innovation of successors. As you know that those who celebrate the birthday of the Prophet   do not fast on Monday; rather they make it a day of feasting in which they eat huge and delicious meals and drink various drinks. This practice proves that they have ignored the authentic Sunnah (Prophetic tradition) and that they are completely adhering to innovations. For more details, please refer to Fatwas 81765 and 81804.

Allaah Knows best.