In his sermons, Ibn Toumert preached the future emergence of a "Mahdi", purifier of the Almoravid empire s' practices, which, according to Ibn Toumert, were corrupt. The Mahdi would be accompanied by a disciple and both would start a salvation crusade from some mysterious place in the Western Maghreb called: TINMEL.

The prophesy becomes a reality the day when he encountered Abdelmoumen (whom he immediately identifies as the disciple), and when he received two mysterious messengers from… Tinmel, without any delay, they set forth for this destination (Tinmel). The count down for the Almoravids had began.

Ibn Toumert and Abdelmoumen met in 1118 at Mellala (not far from Bougie, Algeria) under the following circumstances: " that day, the Mahdi was sitting under the same tree ….., whispering the same prayers; suddenly, he stood up and exclaimed " Praised be Allah, He has fulfilled His promise and has assisted His servant. His order has been carried out " He then got into the mosque, made two genuflections and declared to his companions " … the moment of victory has come, and there is no victory but that which Allah allows… Tomorrow, a taleb will come to you ; happy are those who will recognize him; miserable are those who will deny him!" (Al Baidaq, cited by H.Triki).

The same eyewitness (Al Baidaq) of the encounter between the master and his disciple says: " when the night had come, The Perfect Imam took the hand of the future caliph , and both went walking in the middle of the night. The Perfect Imam said to me: “give me the book in the red box, turn on a candle… and while I was holding the lamp, I heard him saying:" … Islam will not triumph but by Abdelmoumen Ibn Ali, torch bearer of the Almohads!

Hearing these words, the future caliph started weeping, and said:

-“ O Fakih, I'm not qualified for this role, I'm but a man looking for purification from his sins!”

-“what is going to purify you is the role you will play in the reformation of this wicked world…. happy are the man of whom you will be the leader and miserable are those who will be opposed to you…” replied the (Perfect) Imam handing him the book (cited by Triki).

The future sovereign of the vastest Moroccan empire of all times had taken that night the path which would lead him towards a prestigious destiny. Some years later, official letters signed : Abdelmoumen Ibn Ali, Caliph and commander of the faithful, were sent to Spain and the Maghreb from the " Sublime Residence" , Tinmel. (H. Triki).