An example of the Faith and a life of humility, as a teacher of abstinence you did inspire and lead your flock, and through the truthfulness of your deeds were exalted by greatness, through your humility uplifting all and by poverty gaining wealth. Father and hierarch Nicholas, intercede with Christ our God that our souls be saved.

The text certainly carries the sound of antiquity, although there is no date given at the site. So do the original Greek and other translations at the same website, with one reference to the Sarum Rite Missal (11th c. English gathering of Church tradition at Salisbury). My guess is that this hymn predates the Sarum use by a long time.

At any rate, I set the hymn to poetry, taking a few liberties in relating to the legends and—given the suggested context of a children's sermon—pointing St. Nicholas and giving in the way of the manger. I commend it to your use, having both children and congregation sing at the end of the children's sermon—tune PUER NOBIS, WINCHESTER NEW or any other Long Meter (LM) tune of your choosing.