Siman 72, The Great Holiness of Shabbos, One Who Desecrates It is Like an Idolator, Halachos Dealing with Bringing in Shabbos, Paragraph 20-end of the Siman and Siman 73, The Conditions where it is Permitted to Give Work to a Non-Jew on Friday and to Lend or Rent Vessels to him on Friday, Paragraphs 1-4.