John Calvin Commentary Exodus 6:14

"These are the heads of their fathers` houses. The sons of Reuben the first-born of Israel: Hanoch, and Pallu, Hezron, and Carmi; these are the families of Reuben." — Exodus 6:14 (ASV)

These are the heads. The purpose of Moses here is to testify to all ages about the origin of his people, so that no one may doubt that, in the free departure of the people, the promise given to Abraham was completed. For if the Israelites had gone forth under any other leader, there might have been some question as to the chief author of it; now, since Moses was chosen from that family, and from the posterity of Abraham, it more clearly appears that the whole matter was accomplished under the guidance of God.

But although he enumerates not only the tribe of Levi, but begins with Reuben the first-born, and then adds Simeon, it is still easily seen that he especially refers to the tribe of Levi. Yet, because the families of Reuben and Simeon came first in order, he appropriately proceeds from them to the third. He does not, however, recount the others at present, because a more favorable opportunity would occur later.

This, then, is the point to be observed: that the minister of their deliverance, by whose hand God would ratify the truth of His promise, was chosen from the lineage of Abraham. And certainly we see how Satan in opposition has obscured, through secular writers, this memorable history with many fables, and especially when he cunningly endeavors to bury the lineage of Abraham. Moses, by divine wisdom, anticipates this subtlety, mentioning the heads of the families by name, so that there would be no obscurity about the origin of the nation.