It is narrated from Sayyiduna Yazid bin Amir al-Suwa'i (may Allah be pleased with him) that he said: On the day of the Battle of Hunayn, when the Muslims fell into disarray (and retreated), the disbelievers pursued them. So the Messenger of Allah (peace and blessings be upon him) took a handful of earth from the ground, threw it at their (the disbelievers') faces and said: "Go back! May these faces be disgraced!" (Since Yazid bin Amir was in the army of the disbelievers at that time, he relates that the effect of that handful was that) whenever any of us met a companion of his, he would be complaining of grit (dust or a speck) in his eye and rubbing his eyes.
Al-Tabarani (may Allah have mercy on him) recorded it, and all of its narrators are thiqat (trustworthy).