Buuxi weedha soo socota: "Zawiya al-Fassiya" ee ugu horreysay waxaa markii ugu horreysay aasaasay awoowe Abdelkader, Abu al-Mahasin (oo dhintay 1604), oo ah aqoonyahan Muslim ah oo ka yimid Ksar el-Kebir iyo qoys reer burjuus ah oo asal ahaan ka soo jeeda Andalusi. Ka hor inta uusan imaanin Fees, Abu al-Mahasin wuxuu raali ka noqday suldaankii Saadiyaan Ahmed al-Mansur mahadsanid dagaalyahanadii uu u diray inay la dagaalamaan
Dagaalkii Ksar el-Kebir (oo sidoo kale loo yaqaan Dagaalkii Saddexda Boqor) 1578. Wuxuu u guuray Fes 1580 wuxuuna bilaabay zawiya isagoo wax ku baraya gurigiisa oo ku yaal xaafadda al-Mukhfiya (ee xaafadda Andalusiyyin ee magaalada), taas oo si dhakhso leh ugu soo baxday xarun muhiim ah oo waxbarasho u gaar ah. Abu al-Mahasin wuxuu iibsaday guryo deris ah si uu ugu habboonaado ballaarintiisa 1596 wuxuu mid ka mid ah guryaha u beddelay masaajid loogu talagalay zawiya, isagoo u magacaabay wiilkiisa Abu al-Abbas Ahmad al-Hafiz inuu noqdo imaam. Waxbarashadii zawiya waxay raacday iskuulka fikirka ee al-Jazuli (isaga oo ku jira amarka Shadhili) iyo kuwa Abd al-Rahman al-Majdub (oo dhintay 1569), oo ahaa sheikh hore oo Sufi ah oo waqti ku qaatay Fes oo ahaa macallinka Abu al-Mahasin.