Did Moses have a speech impediment?

What Moses says at the bush

God has just given Moses his mission and answered three of his objections. Moses tries a fourth.

Moses said to Yahweh, “O Lord, I am not eloquent, neither before now, nor since you have spoken to your servant; for I am slow of speech, and of a slow tongue.”

The Hebrew is kevad peh ukhevad lashon, “heavy of mouth and heavy of tongue.” It says how he speaks, not why. Hebrew did have a word for stammerers: Isaiah promises that “the tongue of the stammerers will be ready to speak plainly” (Isaiah 32:4). Exodus never uses it for Moses.

God’s answer

God doesn’t deny the problem. He answers with a question.

Yahweh said to him, “Who made man’s mouth? Or who makes one mute, or deaf, or seeing, or blind? Isn’t it I, Yahweh? Now therefore go, and I will be with your mouth, and teach you what you shall speak.”

Moses tries once more: “Oh, Lord, please send someone else” (4:13). God’s anger burns, but he gives Moses a partner. His older brother Aaron “can speak well,” and he will be Moses’s mouth (4:14–16). Two chapters later Moses is still protesting that he has “uncircumcised lips” (Exodus 6:12, 30). Jeremiah uses the same picture for ears that cannot hear (Jeremiah 6:10): an organ that doesn’t work as it should.

Three ways to read it

Readers have explained the heavy tongue in very different ways.

• A burned tongue. A famous Jewish legend in the midrash Exodus Rabbah (1:26) says that as a small child in the palace, Moses took the crown off Pharaoh’s head. The king’s advisers set a test: put gold and a burning coal in front of him and see which he grabs. An angel pushed his hand to the coal, he put it to his mouth and burned his tongue. That, says the legend, is why he spoke heavily.
• A foreign tongue. God tells Ezekiel he is not sent to a people “of a strange speech and of a hard language” (Ezekiel 3:5), and the Hebrew there is the same “heavy of tongue,” for a language you can’t follow. Moses had spent decades in Midian. The medieval commentator Rashbam thought he meant his Egyptian was no longer fluent.
• Modesty. Prophets in the Bible often shrink from the call. Jeremiah says, “I don’t know how to speak; for I am a child” (Jeremiah 1:6). Isaiah calls himself “a man of unclean lips” (Isaiah 6:5) before he says “Here I am. Send me!”. Many scholars read Moses’s protest as part of the same pattern.

The man who did the most talking

Whatever the problem was, the story soon stops mentioning it. As the plagues go on, Moses speaks to Pharaoh himself, and gets the last word: “You have spoken well. I will see your face again no more” (Exodus 10:29). Stephen, in Acts, calls him “mighty in his words and works” (Acts 7:22). Most of Deuteronomy is one long farewell speech, which opens, “These are the words which Moses spoke to all Israel” (Deuteronomy 1:1). In Hebrew, “I am not eloquent” is literally “I am not a man of words,” and the midrash Deuteronomy Rabbah (1:1) enjoys the echo: once Moses received the Torah, it says, his tongue was healed.