3 And command ye them, saying, Take you hence out of the midst of Jordan, out of the place where the priests' feet stood firm, twelve stones, and ye shall carry them over with you, and leave them in the lodging place, where ye shall lodge this night.
[AD 395] Gregory of Nyssa on Joshua 4:3-4
The people of the Hebrews, as we learn, after many sufferings, and after accomplishing their weary course in the desert, did not enter the land of promise until it had first been brought, with Joshua for its guide and the pilot of its life, to the passage of the Jordan. But it is clear that Joshua also, who set up the twelve stones in the stream, was anticipating the coming of the twelve disciples, the ministers of baptism.

[AD 410] Prudentius on Joshua 4:3-4
Also, twelve stones from Jordan’s bed,
Left dry when waters backward flowed,
He raised and firmly set in place,
The type of Christ’s apostles twelve.

[AD 450] Peter Chrysologus on Joshua 4:3-4
The twelve patriarchs destined to become twelve tribes were arranged to be a type and pattern of the number of the apostles. So were the twelve fountains4 in the desert and twelve stones taken from the bed of the Jordan. We leave it to the student of the law to find deeper proof of all this.