Exodus 4:12

Now therefore go, and I will be with thy mouth, and teach thee what thou shalt say.

Spoken to Moses as a lowly shepherd sent to stand before Pharaoh and demand in God's name that he let Israel go, the promise means that the God who forms the mouth and makes the dumb, deaf, seeing and blind would Himself accompany his speaking and instruct him what to say. Moses had pleaded lack of eloquence and slowness of speech and tongue from timidity and a sense of incapacity to be God's mouthpiece, after forty years away from Egypt had left him without ready command of its language. The assurance shows that the God who chose him was able to qualify him for the work and had made no mistake in choosing him, removing the difficulty and guaranteeing success. To keep shrinking back and asking for a more competent person after that word was no longer humility but displeasing unbelief and distrust of God, as if He were unable to fit him for the great work to which He called him. When he accepted in simple trust and ready obedience, God blessed him and made the hesitant man eloquent, self-possessed and fruitful, proving that a living connection with God can make even a stammering tongue effective for deliverance beyond all human wisdom and strength.

Moses' Call and Promise

God sent Moses, though he was then a lowly shepherd, to lead Israel out of Egypt, and He made the shepherd's rod a sign of divine power. The commission was to stand before Pharaoh and in God's name demand that he let Israel go, rather than to deliver Israel by warfare with Moses as general, a manner of working Moses had not expected and from which he shrank. When called, Moses pleaded lack of eloquence and slowness of speech and tongue, feeling timid, distrustful, and overwhelmed by incapacity to be God's mouthpiece. That sense of inability came because long absence from the Egyptians — forty years away — had left him without clear knowledge and ready use and command of their language.

The answer was that the Lord who makes man's mouth and makes the dumb, deaf, seeing, and blind would Himself accompany Moses' speaking and instruct him in what to speak. To be with his mouth and teach him what to say meant God would be with him as he spoke and bring to him what he should utter. The promise showed the God who chose Moses to deliver Israel is able to qualify him for the work and made no mistake in choosing him. It removed the difficulty raised about speech and guaranteed success in his mission and final success.

The humility Moses showed had been learned during his years as a shepherd among the mountains tending sheep. Those years had disciplined his former ambition and self-reliance and taught him not to exalt himself but to trust God rather than education or abilities.

Faith, Doubt and Empowerment

At first Moses held back from a humble and modest diffidence, with a very low estimate of his own qualifications, but after God promised to remove the difficulty his continued shrinking back, asking for a more competent person to be sent, and pleading not to be given the responsibility no longer came from humility. His humility had been learned among the mountains while tending sheep, where he did not exalt himself, and he consented only after God convinced him that he was chosen to deliver Israel. To keep holding back after that assurance was displeasing to God and showed unbelief, criminal despondency, and distrust of God Himself. That distrust was rooted in reduced confidence in his own ability, implying fear that God was unable to qualify him for the great work to which he was called or had made a mistake in choosing him, as if deliverance in the manner God proposed looked hopeless of success.

Because Moses did not fully trust the promise to rely on divine help rather than his own speaking ability, Aaron was chosen to speak before Pharaoh. When Moses accepted the work putting all his trust in the Lord, God blessed his ready obedience, called the best powers of his mind into exercise, and strengthened and fitted him for his great mission. He who had felt distrustful, slow of speech, timid, and overwhelmed by incapacity to be God's mouthpiece was thus made eloquent, hopeful, self-possessed, and well fitted.

His change proves what God will do to strengthen the character of those who trust Him implicitly and give themselves unreservedly to His service and obey His commands, giving power and ability to those who rely on Him. He makes a weak man strong and prolific in results through faith in His power and devotion to His service, turning the hesitating and irresolute firm and decided, exalting their nature, opening the mission of Christ before them with new importance and glory, and making them collaborators with the Saviour as instruments for the salvation of souls. The lesson is that human strength and usefulness depend on God rather than on education or abilities, for the years as a shepherd had disciplined former ambition and self-reliance to teach trust in God. Moses must therefore go with simplicity of character, distrust of self, loss of self-confidence, and a sense of utter helplessness and inefficiency without being upheld by Jesus, depending on the invisible Leader as a willing instrument in the hand of Christ.

He must not use his education to argue the unreasonableness of God's commands or the impossibility of obeying them, but obey all God commands whether it seems proper to human reason or not, without stopping to consider consequences. He must change his way for the Lord's way even into strange paths and untried ways, and submit to God's discipline. By such simple, implicit, constant, unflinching faith in God's power and loving intentions, Moses becomes a sanctified, unobstructed channel through whom God can manifest great power. Through that channel God presses through difficulties and overcomes almost insurmountable obstacles and enemies, and brings blessing and deliverance to Israel that all human wisdom, learning, and strength could never accomplish.

Promise for God's Messengers

The promise to be with the mouth and teach what to say belongs not to Moses alone but to all who face difficult responsibilities and feel unable to speak, for God will give fitting words to those who depend on Him rather than on self-confidence and will make those words effective. A close, living connection with God can make even a stammering tongue eloquent. This was seen when Butcher, despite his severe stammer, trusted that God would help him and prayed for help, and then spoke about the truth with freedom and convincing power.

Moses' sense of unfitness and poor estimate of his own fitness when called marks those best qualified to enter the sacred calling to preach, who are often not conscious of their own qualifications. Such humble persons who feel as Moses felt should therefore be sought out, made a subject of prayer, and if it is the mind of the Spirit brought forward with proper recommendation for the ministry. The verse means God never leaves His church without a witness but prepares men to take up His work and gives them His own message to speak. He equips the one He sends by being with him, bringing needed words to mind, and making the message effective through the Holy Spirit.

Christ Himself was the teacher of His ancient people, appearing to them and talking face to face as a man speaks to his friend, veiled as their invisible Leader in the pillar of fire and of cloud and speaking to the people through Moses. To prophets appointed to a special work and a special message He gives words that are not after the ways and will of men, puts His prepared message in their mouths, and sends them to proclaim it and to repeat the same words over and over. He assures them the Holy Spirit will give language and utterance, with He who knows the heart supplying words that will reach the people. God gives the words and guidance needed to speak His message even when the speaker faces strong opposition, so that those words can carry heavenly wisdom and be received as coming from the Lord.

The promise applies to a commission to bear a living testimony and to speak God-given words of warning and reproof to church members and unbelievers. God accompanies and equips the person He sends by giving the words and ability to speak and teaching the messenger what to say. When that testimony is heeded it can lead many to salvation.