Kabbalists say it is a mitzva to sweat while you bake matzot: it counteracts the sweat produced from the exertion of sinning. Less than a week before Pessah, at Biderman's bakery in the heart of Mea She'arim there is a lot of sweating going on. It is not the huge stone oven fired by olive wood that reaches 800 , nor is it a lack of ventilation (all the windows are tightly closed and draped against sunlight that is said to speed the leavening of the dough) that is making them perspire. Rather it is the tense, almost contradictory combination of speed and care needed for baking matza. From the second the small sliding door that separates the water from the flour is opened and the 18-minute countdown - the time rabbis reckon it takes for dough to rise - begins, the tension in the bakery is palpable. "If not for the Torah's commandment to eat matza on Pessah, God-fearing rabbis probably would have forbidden it altogether," jokes a young hassid sitting on a bench resting. "No other food eaten on Pessah comes closer to being hametz [leavened bread]." But the Torah commanded. Now speed and care are the name of the game. "Show me your hands," demands a tense young man with a scraggly beard and a strong Yiddish accent as a group of men walks in to Biderman's to begin baking matzot. "Go wash and scrub them," he barks. "And take off your watches." The men tie plastic aprons around their waists and get to work. But before they begin, they are told to recite the following: "Everything I do to prepare the matzot is done with the purpose of making mitzva matzot." The mixing of the water, the kneading and the rolling of the dough and the baking all must be done with the intention of creating a matza that will be eaten on Pessah eve as commanded in the Torah. The pieces of dough are made small enough to knead thoroughly and constantly. They are placed on a low stainless steel table. A stainless steel bar is attached to the table with a pivoting hinge. The dough is placed under the bar which is brought down firmly again and again. Some of the kneaders jump up and down. The men are careful that the beads of sweat that quickly appear on their foreheads and necks do not drop onto the dough. The supervisors watch the clock. Less than 10 minutes have gone by, but it seems like an eternity for the tiring kneaders. The dough is rolled into the shape of a long sausage and is rushed to the stainless steel rolling tables where it is cut into matza-size pieces. As the 18 minutes expire, the round flat pieces of dough are placed on a long wooden pole and put deep inside the huge oven by a red-faced, stooped man who has been baking matzot at Biderman's since 1946. The final product costs NIS 140 per kilogram - not bad for bread of affliction. "It's worth every shekel," says one of the men in the group as he leaves, the sweat just a pleasant memory.