وَجَآءُوا عَلَى قَمِيصِهِ بِدَمٍ كَذِبٍ
(And they brought his shirt stained with false blood.) on it, to help prove plot that they all agreed on. They slaughtered a sheep, according to Mujahid, As-Suddi and several other scholars, and stained Yusuf's shirt with its blood. They claimed that this was the shirt Yusuf was wearing when the wolf devoured him, being stained with his blood. But, they forgot to tear the shirt, and this is why Allah's Prophet Ya`qub did not believe them. Rather, he told them what he felt about what they said to him, thus refusing their false claim,