Some of these teachings were summarized in texts (in Arabic initially). Important contributions in writing are attributed to Uwais al-Qarni, Harrm bin Hian, Hasan Basri and Sayid ibn al-Mussib, who are regarded as among the first Sufis in the earliest generations of Islam. Harith al-Muhasibi was the first one to write about moral psychology. Rabia Basri was a Sufi known for her love and passion for God, expressed through her poetry. Bayazid Bastami was among the first theorists of Sufism.