Following the sale of Joseph, the brothers faced a critical challenge: crafting a convincing cover story to explain his absence and prevent Jacob from searching for him. If they simply claimed ignorance of his whereabouts, Jacob would undoubtedly send search parties. Conversely, presenting his garment intact would suggest he had merely been robbed but was still alive. To ensure their father would abandon all hope, they needed undeniable proof of a fatal tragedy. To secure this secret, the brothers forged a pact to never reveal the truth unless they received a clear sign from God [אלשיך, חומש קה״ת]. Furthermore, they chose to deliver the evidence through messengers rather than returning it themselves. They feared that if they faced Jacob directly, he might perceive their lingering hatred and suspect them of murder [צאינה וראינה].
The brothers carefully orchestrated their deception. They retrieved the discarded tunic first, acting quickly before slaughtering a young male goat [ביאור שטיינזלץ]. This specific order of events ensured that the fresh blood would not seep into the ground while they went to fetch the garment [העמק דבר].
The primary approach among commentators is that a goat was chosen because its blood closely resembles human blood. This raises a discussion based on a later historical account where a Babylonian general attempted to match goat blood to the spilled blood of a prophet, and the two did not look alike. Commentators offer several ways to reconcile this. Some suggest the prophet's blood had been mixed with other substances, altering its appearance [ריב״א, חזקוני]. Others explain that the difference is only noticeable when the two types of blood are placed side by side; when viewed alone, goat blood easily passes for human blood. Additionally, the brothers used fresh goat blood, whereas the prophet's blood in the later account was old and unsettled [פרדס יוסף]. A different perspective completely dismisses these natural explanations, asserting instead that the later historical event involved a heavenly miracle that prevented the bloods from matching, serving as a consequence for the people's sins [שפתי חכמים, דברי דוד].
Beyond the practical reasons for choosing a goat, the act carried a profound historical irony, operating measure for measure: just as Jacob had once deceived his father, Isaac, using goat skins, his sons now used a goat to deceive him [שפתי כהן].
To complete the illusion, the brothers did more than just stain the fabric. They intentionally tore the garment to mimic the savage attack of a wild beast [שד״ל, צאינה וראינה]. They then plunged the entire tunic into the blood rather than just splashing it. This total saturation was designed to create the impression of massive, fatal wounds, guaranteeing Jacob would conclude his son was dead rather than merely injured [אלשיך].