When Moses finally gave in, and declared himself ready to go to Egypt as God's messenger, his acceptance was still conditional upon the promise of God to fulfil all his wishes, and God granted whatsoever he desired, except immortality and entering the Holy Land. God also allayed his fears regarding the danger that threatened him from his whilom enemies Dathan and Abiram, on account of whom he had had to flee from Egypt. He told him that they had sunk to the estate of poor and insignificant men, bereft of the power of doing him harm.
Moses was loyal to the oath he had given his father-in-law Jethro, never to return to Egypt without securing his consent. His first concern therefore was to go back to Midian and obtain his permission, which Jethro gave freely. Then Moses could set out on his journey. He tarried only to take his wife and his children with him, which made his father- in-law say, "Those who are in Egypt are to leave it, and thou desirest to take more thither?" Moses replied: "Very soon the slaves held in bondage in Egypt will be redeemed, and they will go forth from the land, and gather at Mount Sinai, and hear the words, 'I am the Lord thy God,' and should my sons not be present there?" Jethro acknowledged the justice of Moses' words, and he said to him, "Go in peace, enter Egypt in peace, and leave the land in peace."
At last Moses sallied forth upon his journey to Egypt, accompanied by his wife and his children. He was mounted upon the very ass that had borne Abraham to the Akedah on Mount Moriah, the ass upon which the Messiah will appear riding at the end of days. Even now, his journey begun, Moses was but half-hearted about his mission. He travelled leisurely, thinking: "When I arrive in Egypt and announce to the children of Israel that the end of the term of Egyptian slavery has come, they will say, 'We know very well that our bondage must last four hundred years, and the end is not yet,' but if I were to put this objection before God, He would break out in wrath against me. It is best for me to consume as much time as possible on the way thither."
God was ill pleased with Moses for this artifice, and He spake to him, saying, "Joseph prophesied long ago that the oppression of Egypt would endure only two hundred and ten years." For his lack of faith Moses was punished while he was on the road to Egypt. The angels Af and Hemah appeared and swallowed his whole body down to his feet, and they gave him up only after Zipporah, nimble as a "bird," circumcised her son Gershom, and touched the feet of her husband with the blood of the circumcision. The reason why their son had remained uncircumcised until then was that Jethro had made the condition, when he consented to the marriage of his daughter with Moses, that the first son of their union should be brought up as a Gentile.
When Moses was released by the angels, he attacked them, and he slew Hemah, whose host of angels, however, held their own before the assailant.
The Divine voice heard by Moses in Midian telling him to return to his brethren in Egypt fell at the same time upon the ear of Aaron, dwelling in Egypt, and it bade him "go into the wilderness to meet Moses." God speaketh marvellously with His voice, and therefore the same revelation could be understood one way in Midian and another way in Egypt.
The greeting of the two brothers was very cordial. Envy and jealousy bad no place between them. Aaron was rejoiced that God had chosen his younger brother to be the redeemer of Israel, and Moses was rejoiced that his older brother had been divinely appointed the high priest in Israel. God knew their hearts, for at the time when He charged him with the Egyptian mission, Moses had said, "All these years Aaron has been active as a prophet in Israel, and should I now encroach upon his province and cause him vexation?" But God reassured him, saying, "Moses, thy brother Aaron will surely not be vexed, he will rather rejoice at thy mission, yea, he will come forth and meet thee."
Aaron showed his joy freely at seeing his brother once more, after their separation of many years. As for his joy in the distinction accorded to Moses, it was too great to be expressed in all its depth and extent. For his kind, generous spirit, he received a reward from God, in that he was permitted to bear the Urim and Thummim upon his heart, "for," God said, "the heart that rejoiced at the exalting of a brother shall wear the Urim and Thummim."
Aaron ran to meet his brother, and embraced him, and asked where he had spent all the years of their separation. When he was told in Midian, he continued to question him, saying, "Who are these that are travelling with thee?"
Moses: "My wife and my sons."
Aaron: "Whither goest thou with them?"
Moses: "To Egypt."
Moses recognized that Aaron was right, and he sent his wife and his sons back to his father-in-law Jethro.
He was no less magnanimous than Aaron. If the elder brother felt no envy on account of the younger brother's dignity, the younger brother did not withhold from the other the teachings and revelations he had received. Immediately after meeting with Aaron, Moses told him all that God had taught him, even the awful secret of the Ineffable Name communicated to him on Mount Horeb.
In obedience to the command of God, the elders of the people were assembled, and before them Moses performed the wonders that were to be his credentials as the redeemer sent to deliver the people. Nevertheless, the deeds he did were not so potent in convincing them of the reality of the mission as the words wherein God had announced the approaching redemption to him, which he repeated in their ears. The elders knew that Jacob had imparted to Joseph the secret mark designating the redeemer, and Joseph had in turn confided it to his brethren before his death. The last surviving one of the brethren, Asher, had revealed it to his daughter Serah, in the following words: "He that will come and proclaim the redemption with the words of God, 'I have surely visited you, and seen that which is done to you in Egypt,' he is the true redeemer." Serah was still alive at Moses' return, and the elders betook themselves to her, and told her the words of Moses announcing the redemption. When she heard that his words had been the same as those Asher had quoted, she knew that he was the promised redeemer, and all the people believed in him.
Thereupon Moses invited the elders to go to Pharaoh with him, but they lacked the courage to appear before the king. Though they started out with Moses, they dropped off stealthily on the way, one by one, and when Moses and Aaron stood in the presence of the king, they found themselves alone, deserted by all the others. The elders did not go out free. Their punishment was that God did not permit them to ascend the holy mountain with Moses. They durst accompany him on the way to God only as far as they had accompanied him on the way to Pharaoh, and then they had to tarry until he came again.