What is the meaning of the phrase: "Nor shall you bring a slander that you have invented between your hands and feet," which is mentioned in the First Pledge of Aqabah?

"Buhtan" (slander/calumny) is a comprehensive term for anything, whether words or unexpected actions, that astounds and bewilders its victim. It is not exclusive to women. It includes adultery, backbiting, tale-bearing, slandering chaste women, giving false witness, attributing a child to other than his father, and sorcery. All of these are major sins.