Albert Barnes on Matthew 6:30

Is cast into the oven. The Jews had different modes of baking. In early times they frequently baked in the sand, warmed with the heat of the sun. They constructed also moveable ovens, made of clay, brick, or plates of iron. But the most common kind, and the one here probably referred to; was made by excavating the earth two and a half feet in diameter, and from five to six feet deep. This kind of oven still exists in Persia. The bottom was paved with stones. It was heated by putting wood or dry grass into the oven; and when heated, the ashes were removed, and the bread was placed on the heated stones. More commonly, however, the oven was an earthen vessel, without a bottom, about three feet high, smeared outside and inside with clay, and placed upon a frame, or support. Fire was made within it, or below it. When the sides were sufficiently heated, thin patches of dough were spread on the inside, and the top was covered, without removing the fire as in the other cases; and the bread was quickly baked. The preceding representation of it is taken from Niebuhr.