Musannaf Ibn Abi Shaybah

Hazrat Muhammad bin Ishaq states that Hazrat Qasim was asked about a man who says to someone: "O son of a tailor," or "O son of a cupping practitioner," or "O son of a butcher," while in fact his father is not such—what is the ruling regarding this? Upon this, Hazrat Qasim replied: Indeed, we found that punishments were not carried out except in the case of a clear accusation or in the case of an explicit denial.