Jacob of Nisibis

Righteous

Commemorated January 13 · October 31

Our Righteous Father Jacob of Nisibis , also James of Nisibis , Jacob the Great , Jacob of Mygdonia , or Mor Ya`qub , called the " Moses of Mesopotamia" for his wisdom and wonderworking abilities, was the second bishop of Nisibis, spiritual father of the renowned Syriac writer and theologian Ephrem the Syrian , celebrated ascetic and one of the 318 fathers of the First Ecumenical Council at Nicaea.
His feast days in the Orthodox Church are January 13 /26 and October 31 /November 13.

Source: OrthodoxWiki