The custom of reciting BaMeh Madliqin, the second chapter of Mishnah Shabbat, on Friday nights probably originated as an anti-Karaite polemic. While the Karaites were opposed to any use of fire on Shabbat, rabbinic Jews kindle lights before Shabbat, and the recitation of BaMeh Madliqin — the laws of Shabbat lights — emphasized this distinction. One of the best firsthand sources we have for this is the following introductory blessing from the Cairo Genizah (T-S NS 299.150 verso) for the recitation of BaMeh Madliqin, first published by Naftali Wieder in this article. This blessing emphasizes the continuity of the Torah both written and oral from Sinai to the sages and elders.