God called Moses to deliver Israel from Egyptian slavery.
At the age of 80 (see Exodus 7:7), GOD called Moses to lead Israel out of Egyptian slavery.
These events are recorded in Exodus 3-4. GOD appeared to Moses and got his attention through a burning bush that, miraculously, was not consumed by the fire.
3:1 Now Moses was tending the sheep of Jethro his father-in-law, the priest of Midian. Then he led them to the back of the desert and came to Horeb, the mountain of God. 2 Then the Angel of the Lord appeared to him in a flame of fire from the midst of a bush. So he saw the bush burning with fire, but the bush was not consumed. 3 So Moses said, “I will now turn aside and see this great sight, why the bush is not consumed.”
4 When therefore the Lord saw him turn aside to look, God called to him from the midst of the bush and said, “Moses! Moses!” Then he said, “Here I am.” 5 So He said, “Do not come any closer. Take your sandals off your feet, for the place where you stand is holy ground.” 6 Moreover He said, “I am the God of your father—the God of Abraham, the God of Isaac, and the God of Jacob.” Moses then hid his face, for he was afraid to look at God.
7 Then the Lord said, “Indeed, I have seen the affliction of My people in Egypt, and have heard their cry because of their taskmasters; for I know their sorrow. 8 So I came down to deliver them out of the hand of the Egyptians and to bring them up from that land to a good and large land, to a land flowing with milk and honey, to the place of the Canaanites, the Hittites, the Amorites, the Perizzites, the Gergesites, the Hivites, and the Jebusites. 9 Now therefore, behold, the cry of the children of Israel has come to Me, and I have also seen the affliction with which the Egyptians oppress them. 10 Come now, I will send you to Pharaoh, to bring My people, the children of Israel, out of the land of Egypt.”
11 But Moses said to God, “Who am I to go to Pharaoh, king of Egypt, to bring the children of Israel out of the land of Egypt?” 12 Then God said to Moses, “I will be with you, and this shall be a sign to you that I have sent you: When you have brought the people out of Egypt, you shall serve God on this mountain.” 13 So Moses said to God, “Indeed, when I go to the children of Israel and say to them, ‘The God of your fathers sent me to you,’ and they ask me, ‘What is His name?’ what shall I tell them?”
14 Then God said to Moses, “I AM the Existing One.” He also said, “Thus you shall say to the children of Israel: ‘The Existing One sent me to you.’” 15 Moreover God said to Moses again, “Thus you shall say to the children of Israel: ‘The Lord God of your fathers—the God of Abraham, the God of Isaac, and the God of Jacob—sent me to you.’ This is My name forever, and My memorial to all generations. 16 Go then, and gather the elders of the children of Israel together and say to them, ‘The Lord God of your fathers—the God of Abraham, the God of Isaac, and the God of Jacob—appeared to me, saying, “I have surely looked upon you and all the things that happened to you in Egypt; 17 and I will bring you up out of the affliction of Egypt to the land of the Canaanites, the Hittites, the Amorites, the Perizzites, the Gergesites, the Hivites, and the Jebusites, to a land flowing with milk and honey.’”
18 “Then they will heed your voice; and you shall go, you and the elders of Israel, to the king of Egypt; and you shall say to him, ‘The God of the Hebrews met with us; and now, let us go three days’ journey into the desert to sacrifice to our God.’ 19 But I know Pharaoh the king of Egypt will not let you go, not even by a mighty hand. 20 Thus I will stretch out My hand and strike the Egyptians with all My wonders which I will work among them; and after that he will let you go. 21 Then I will give this people grace in the sight of the Egyptians; and when you go, you shall not go empty-handed. 22 But every woman shall ask of her neighbor, namely, of her who dwells near her house, articles of silver, gold, and clothing; and you shall put them on your sons and daughters. Thus you shall plunder the Egyptians.”
4:1 Then suppose they say, ‘The Lord did not appear to you.’” 2 So the Lord said to him, “What is in your hand?” He said, “A rod.” 3 Thus He said, “Cast it on the ground.” So he cast it on the ground, and it became a serpent; and Moses fled from it. 4 Then the Lord said to Moses, “Reach out your hand and take it by the tail” (so he reached out his hand and caught it, and it became a rod in his hand), 5 “so they may believe the Lord God of their fathers—the God of Abraham, the God of Isaac, and the God of Jacob—appeared to you.”
6 Furthermore, the Lord said to him, “Now put your hand in your bosom.” So he put his hand in his bosom, and when he took it out, it was leprous like snow. 7 Again He said, “Put your hand in your bosom” (so he put his hand in his bosom again and then removed it; and it was restored to the complexion of his other flesh), 8 “then it will be, if they do not believe you, nor heed the message of the first sign, they may believe the message of the second. 9 Then it shall be, if they do not believe even these two signs or listen to your voice, you shall take water from the river and pour it on the dry land; and the water you take from the river will become blood on the dry land.”
10 Then Moses said to the Lord, “I pray, O Lord, I am not capable, neither before nor since You spoke to Your servant; but I am weak in speech and slow of tongue.” 11 So the Lord said to him, “Who made man's mouth? And who made the mute, the deaf, the seeing, and the blind? Did not I, God? 12 Now therefore, go, and I will open your mouth and teach you what you shall say.” 13 But he said, “I pray, O Lord, appoint another capable one whom You may send.”
14 Then the Lord was very angry with Moses, and He said, “Is not Aaron the Levite your brother? I know he will speak for you, and indeed, he will come out to meet you; and indeed, when he sees you, he will be glad in heart. 15 Now you shall speak to him and put My words in his mouth, and I will open your mouth and his mouth; and I will teach you what you shall do. 16 So he shall be your spokesman to the people, and he himself shall be your mouth; and you shall be to him as God. 17 Now you shall take in your hand the rod that was turned into a serpent, with which you shall work miracles.”
18 So Moses went and returned to Jethro his father-in-law, and said to him, “I will go and return to my brethren in Egypt and see whether they are still alive.” And Jethro said to Moses, “Go in peace.” 19 Now in those days, after some time, the king of Egypt died. So the Lord said to Moses in Midian, “Go, return to Egypt; for all the men who sought your life are dead.” 20 Then Moses took his wife and sons and set them on beasts of burden; and he returned to the land of Egypt, and Moses took the rod of God in his hand. 21 Again, the Lord said to Moses, “When you go back to Egypt, see that you work before Pharaoh all the wonders I put in your hand. But I will harden his heart, and he will not let the people go. 22 Then you shall say to Pharaoh, ‘Thus says the Lord: “Israel is My firstborn son. 23 So I say to you, ‘Let My people go so they may serve Me.’ But if you refuse to let them go, indeed, I will kill your firstborn son.”’”
24 Thus it came to pass on the way, at the inn, that the Angel of the Lord met him and sought to kill him. 25 Then Zipporah took a sharp stone and cut off the foreskin of her son, and fell at His feet and said, “The flow of blood from my son's circumcision is stopped.” 26 So He departed from him, because she said, “The flow of blood from my son's circumcision is stopped.” 27 Now the Lord said to Aaron, “Go into the desert to meet Moses.” So he went and met him on the mountain of God, and they kissed one another. 28 Then Moses reported to Aaron all the words of the Lord which He sent to him, and all the signs which He commanded him. 29 Thus Moses and Aaron went and gathered together the elders of the children of Israel. 30 Aaron then spoke all the words the Lord spoke to Moses, and he did the signs in the sight of the people. 31 So the people believed and rejoiced because God had visited the children of Israel and because He had seen their affliction. Then the people bowed and worshiped.
(Exodus 3:1-4:31 OSB)
Moses made multiple excuses to GOD as to why he was not qualified or good enough. But GOD qualifies those He calls.