“Yahweh.” This is one of the verses that shows that the name “Yahweh” was known by the people of God from the earliest times. Some scholars assert that God’s name Yahweh (it may have been pronounced differently) was a later development, but it is used in the records in Genesis from earliest times. Words such as Elohim and El Shaddai are not names, they are titles. “Yahweh” is the only actual name of God in the Bible.
What is about to happen is that Moses, who has been gone from Israel for 40 years, is about to go back to Egypt and try to convince the Israelites that the God they have been crying out to for many years has now heard them, met with Moses, and sent him back to deliver them. If Moses comes in the name of some strange god that was not the God of Abraham, Isaac, and Jacob, it could well be that Israel would have rejected him. Moses must come in the name of God that Israel is familiar with, and with signs to prove that Yahweh has indeed met with him and empowered him to deliver Israel from Egypt. When Moses did come back to Egypt in the name of Yahweh and with signs, the Israelites welcomed him. But Moses thought that the Israelites might say, “Yahweh has not appeared to you” (Exod. 4:1).
“Abraham...Isaac…Jacob. God made His covenant with Abraham, and reconfirmed it with Isaac and Jacob. The reason God mentions them in this context is that it emphasizes the covenant that God made with the “Fathers,” which included giving them the land of Israel, so the Israelites would have to be delivered from Egypt for the covenant to be fulfilled.