I think the key is “make Myself known”. That is, God said His holy Name, but Abraham was not aware that that was His Name. Here is
Haydock:
“Ver. 3. My name Adonai. The name which is in the Hebrew text, is that most proper name of God, which signifieth his eternal self-existent being, (Exodus iii. 14,) which the Jews, out of reverence, never pronounce; but instead of it, whenever it occurs in the Bible, they read Adonai, which signifies the Lord; and therefore they put the points or vowels, which belong to the name Adonai, to the four letters of that other ineffable name, Jod, He, Vau, He. Hence some moderns have framed the name Jehovah: unknown to all the ancients, whether Jews or Christians: for the true pronunciation of the name, which is in the Hebrew text, by long disuse, is now quite lost. (Challoner) — This name was first clearly revealed to Moses, that he might have confidence in his special protection and love. (Menochius) — To know one by his name is to treat him with familiarity and distinction, Exodus xxxiii. 17. The pronunciation of the name of God might be known to Abraham, &c., but it was not so fully explained, nor the power and excellence of it declared in such a stupendous manner, as it was to Moses. (Du Hamel)”
I believe that is the right understanding…
“— Or perhaps Moses made use of this name in the history of the patriarchs, because he wrote his account of them after this revelation. (Calmet)”
But this I believe must be rejected. Moses used the Name in what he wrote, as carried by the Spirit, but when he quoted God he clearly is telling us that God revealed His Name to Abraham. But Abraham might have simply heard, “I am who I am, who brought you out…” - not understanding that that was the Name of God. There is also a possibility that God posed a rhetorical question to Moses: “did I not make Myself known to them?” But Fr. Haydock doesn’t mention this possibility, probably because there is no Patristic support for it, so I would go with the former explanation. Here is the rest:
“— The Septuagint always put Kurios, “the Lord,” instead of the ineffable name; and our Saviour and his apostles, citing text where it occurs, follow their example. (Matthew iv. 7, 10; Romans xv. 11.) (Worthington) — Philo informs us, that it was death to pronounce it out of the temple, and since that was destroyed, it has never been heard. (Calmet) — Galatinus, who wrote in 1518, is supposed to have invented the word Jehovah, (see Amama Antib. p. 319,) the year after the pretended reformation began. (Haydock) — St. Jerome (ep. 136 ad Marc.) explains the ten names of God, but never reads Jehovah. (Tirinus)”
