In 1354, he withdrew to live in silence at the monastery he had built in honor of St Mamas at Tenedos. Later, he was elevated to the Patriarchal throne once again (1355-1363). The holy Patriarch Callistus reposed in the year 1363 in Serbia, where he had travelled with an embassy of Emperor John Paleologos. St Callistus is also known as a spiritual writer, and his edifying works appear in the PHILOKALIA with the writings of his close friend Ignatius of Xanthopoulos.
Troparion — Tone 4
You appeared to your flock as a rule of faith, / An image of humility, and a teacher of abstinence. / Because of your lowliness, heaven was opened to you; / Because of your poverty, riches were granted to you! / O Holy Patriarch Kallistos, pray to Christ our God to save our souls!