Discipleship and Episcopate
According to Rhygyfarch's hagiography of Saint David, Ismael was one of the three principal disciples of Dewi Sant. The Book of Llandaff additionally included him among the students of Dubricius and Teilo, tying his formation to the leading figures of the Welsh 'Age of the Saints.'
He is said to have succeeded David as bishop of Menevia (St Davids), though he does not appear in the parish records for that see. The scholar William Jenkins Rees suggested that Ismael was at most a suffragan (auxiliary) bishop under Teilo, and that his own see lay in Rhos, at present-day St Ishmaels in Pembrokeshire.