Yes, and it burned his mouth and tongue and made talking difficult. This story is in the Koran and Rabbinical texts, not in the Bible. He was a baby, he upset the pharaoh, they were going to kill him, someone said "he's a baby, maybe he doesn't know what he's doing. Let's test him.", they put out some gold and a hot coal, he began reaching for the gold but the angel Gabriel guided his hand to the coal which he grabbed and popped into his mouth like babies do with everything. That's why he is slow of speech.)