Many Western Rite Catholics, even the Mass-going, believing and pious, don't seem to realize that the Church venerates many persons from Old Testament times as saints. The Martyrology, old and new, contains many of the more famous such characters (as does the Menaion of the Byzantine Rite, in its Synaxarion - scroll down to find it here); St Joshua the Patriarch, or "Holy Prophet Joshua", appears in both Eastern and Western lists on the 1st of September: and that is when I keep his feast.
I have previously arranged for a priest to celebrate a Votive Mass of St Joshua on or around that day (licit in both old and new rites, I mean, "the extraordinary and ordinary forms of the one Roman Rite"), but didn't get around to it this year.
Here is a proper Kontakion and Troparion (from the common of prophets) for St Joshua, dug up after long searching (thanks to O Great Mystery):
Chosen by Moses to lead the People of God into the Promised Land, you led them through the waters of the Jordan. Thus by your actions as well as by your name you foreshadow the Saviour, who leads us through the waters of Baptism. O Holy Prophet Joshua, beg him now to save our souls!
We honour your prophet Joshua, O Lord; by his prayers, save our souls.
In default of finding an existing proper Collect, here's one I cooked up earlier (for private use only):
O Lord God of hosts, who didst still the sun and moon in their courses at the prayer of blessed Joshua, the leader of thy people Israel; mercifully grant that through his merits and intercession we may never turn from thy law, but, overcoming the enemy in battle by thy grace, come at last into the promised land of heaven. Through Christ our Lord. Amen.
Anyone who happens upon this, remember me if you happen to use these prayers, the Lord will repay you.