754–775), in 744, before the Abbasid Revolution.[7][8][9] Muhammad was often called "the Pure Soul" (al-Nafs al-Zakiyya) for his noble character, but he was also "a somewhat unworldly, even romantic, individual" (Hugh N. Kennedy) and apparently less capable or learned than his younger brother Ibrahim.[10][11][12] When the Abbasids took power, the two brothers refused to accept what they regarded as the usurpation of their legitimate rights and went into hiding. From there they continued their work of proselytism, which reportedly brought them as far as the Sindh, although mostly they stayed in Arabia. The first Abbasid caliph, al-Saffah (r.