Shaykh Tahir ould al-Hajj Muhammad Ould Fahfu al-Massumi (c. 1913[1] – July 17, 2018[2]), Sidi Muhammad Bin Salik Ould Fahfu al-Amsami, better known as Murabit al-Hajj[3] was a Mauritanian Islamic scholar who devoted his life to worship, learning and teaching Islamic sciences.

Based in a remote village in Mauritania, he trained hundreds, if not thousands of scholars, including Hamza Yusuf.

[4] In the 1930s, Sidi Salik Ould Fahfu travelled to Mecca on foot to perform the Hajj; when he returned, he was given the title, Murabit al-Hajj.

[5] In 2016, he was selected by The Royal Islamic Strategic Studies Centre amongst 'The 500 Most Influential Muslims'.

He was married to Maryam Bint Muhammad al-Amin Ould Muhammad Ahmad Bwayba Maryam Bint Bwayba, who memorized the entire Qur’an as well as the basic Maliki texts and Imam al-Nawawi's book of prayers and supplications (Kitab al-Adhkar).