Rise through the Serbian hierarchy
Gabriel entered church service and advanced through the episcopate of the Serbian Patriarchate of Peć. He became Metropolitan of Smederevo and, in 1643, was elected Metropolitan of Raška. Around 1644 he rebuilt the Monastery of the Holy Archangels in the Kovilje Mountains.
After the death of Patriarch Pajsije I in 1647, Gabriel was elected patriarch in 1648. He held the office until 1655, succeeding Pajsije I and preceding Maksim I in the line of restored patriarchs of Peć (1557–1766).
Mission to Russia
In 1653 Gabriel resolved to travel to Russia to seek material support for the hard-pressed Serbian Patriarchate. According to the account, he met Metropolitan Arsenije of Herzegovina on Christmas Eve, then proceeded to Wallachia, reaching Târgoviște, where he attempted to reconcile Wallachian Prince Matei Basarab with the Cossack Hetman Bohdan Khmelnytsky.
Traveling on to Russia in 1654, he carried two books intended for printing: the Lives of Serbian Emperors and Patriarchs and the Typikon against Latin Heresy of Saint Nil Kabasilas. He was received by the Russian Patriarch Nikon and the tsar. In 1658 he took part in the Moscow Synod that approved Nikon's reforms, and afterward decided to remain in Russia.
Martyrdom and veneration
Gabriel returned to the Ottoman Empire in 1659, where he was accused of bearing responsibility for the Russo-Turkish War and of attempting to convert Turks to Christianity. Brought before tribunals and ordered to embrace Islam, he refused.
He was executed at Bursa on July 18, 1659. The presbyter Pavle retrieved and buried his remains. He is venerated by the Orthodox Church as a hieromartyr and was canonized as a saint of the Serbian Orthodox Church; his feast is kept on December 13, with August 30 also appearing in the calendar.
