Bede

For as a sacrament of this the children of Israel once used to encamp about the Tabernacle, so that on each of the four sides of the square three tribes were stationed. Now three times four are twelve, and in three bands of four the Apostles were sent to preach, that through the four quarters of the whole world they might baptize the nations in the name of the Father, the Son, and the Holy Ghost. It goes on: And he gave them power, &c. …

Catena Aurea by Aquinas ↗