Exodus 3:1–8 describes the initial contact between Moses and God. This occurs in one of Scripture’s most memorable scenes: the burning bush. Moses is tending sheep for his father-in-law in Midian, after fleeing from Egypt some forty years prior. He sees a bush which is covered in fire, but not being burnt up. Out of this flame, ”the angel of the LORD” speaks, declaring God’s intent to liberate Israel from their slavery in Egypt.
For a more detailed summary select the link below.
“Exodus 3:1” BibleRef.com
Now Moses was keeping the flock of Jethro, his father-in-law, the priest of Midian, and he led the flock to the back of the wilderness, and came to God’s mountain, to Horeb.