Spiritual Gifts Volume 3 Page 195:
"The Lord directed Moses to say unto Pharaoh, "Thus saith the Lord, Israel is my son, even my first-born. And I say unto thee, Let my son go, that he may serve me. And if thou refuse to let him go, behold, I will slay thy son, even thy first-born." The Lord called Israel his first-born, because he had singled them out from all people to be the depositaries of his law, the obedience of which would preserve them pure amidst idolatrous nations. He conferred upon them special privileges, such as were generally conferred upon the first-born son.
As Moses journeyed to Egypt, the angel of the Lord met him and assumed a threatening posture, as though he would slay him. He was fearful of his life. He had yielded to the refusal of his wife to have their son circumcised, and, in compliance with her wishes, had neglected to obey God. His wife, fearful that her husband might be slain, overcame her feelings of undue affection for her son, and performed the act herself. After this, the angel let Moses go. In his mission to Pharaoh, he was to be placed in a perilous position, where his life would be exposed to the will of the king, if God did not by his power, through the presence of his angels, preserve him. While Moses was living in neglect of one of God's positive commands, his life would not be secure, for God's angels could not protect him while in disobedience. Therefore, the angel met him in the way and threatened his life. He did not explain to Moses why he assumed that threatening aspect. Moses knew that there was a cause. He was going to Egypt according to God's express command, therefore the journey was right. He at once remembered that he had not obeyed God in performing the ordinance of circumcision upon his youngest son, and had yielded to his wife's entreaties to postpone the ceremony. After he had obeyed the command of God he was free to go before Pharaoh, and there was nothing in the way to hinder the ministration of angels in connection with his work.
