God spoke to Moses and said to him, 'I am YHVH.
Vayedaber Elohim el-Moshe vayomer elav ani Adonay.
||I revealed Myself to Abraham, Isaac and Jacob as God Almighty (El Shaddai), and did not allow them to know Me by My name YHVH.
Va'era el-Avraham el-Yitschak ve'el-Ya'akov be'El Shaday ushmi Adonay lo nodati lahem.
||I also made My covenant with them, [promising] to give them the land of Canaan, the land of their pilgrimage, where they lived as foreigners.
Vegam hakimoti et-briti itam latet lahem et-erets Kena'an et erets megureyhem asher garu vah.
|I am YHVH|
To be pronounced 'Lord' or 'God.' See note on Exodus 3:15.
See Genesis 17:1, 35:11, 48:3, 28:7.
|did not allow them...|
Actually, God did use the Tetragrammaton (YHVH) in speaking to Abraham (Genesis 15:7) and Jacob (Genesis 28:13). The name was also used by angels (Genesis 16:11, 19:13,14, 18:14), by the Patriarchs themselves (Genesis 14:22, 15:2, 15:8, 16:2, 16:5, 22:14, 24:27, 24:31, 24:40, 24:44, 24:48, 26:22, 27:7, 27:27, 28:31, 29:32, 33:35, 30:24, 30:30, 32:10, 49:18), and even by gentiles (Genesis 24:3, 24:31, 26:28,29, 30:27, 31:49). It is true, however, that the Tetragrammaton was never used in speech before the time of the Patriarchs. Among the Patriarchs, the Tetragrammaton was known, but not its inner significance (Ramban; Ibn Ezra). This was because the Patriarchs received their prophecy from the level associated with the name El Shaddai, while only Moses received it from the level associated with the Tetragrammaton (Moreh Nevukhim 2:35; Ralbag; Milchamoth HaShem 6). Knowing God's name in the true sense is something great, as we see in Isaiah 52:6, Jeremiah 31:33, Psalms 83:19.