The miracle of lice was also manifested in the case of the Holy Prophet (S). When the Messenger of Allah (S) declared his prophethood in Medina and his position strengthened, one day His Eminence (S) was giving a discourse about how Allah had taken the trial of His apostles to see whether they remained patient in calamities.
He mentioned that between the Rukn and Maqam are buried seventy prophets who died of hunger and lice. The Jews, hypocrites and the wicked Quraish heard this and decided among themselves that they will eliminate the Prophet and join him with those prophets so that he may not continue to fabricate such things. So they decided that when they find him alone outside Medina, they would surround him and finish him off. T
hey were two hundred men who had devised this plot. One day His Eminence (S) went alone out of Medina and they followed him. Suddenly one of them saw lice on his clothes and on account of this he began to scratch his body and back. He felt ashamed of his companions and went away from them. One by one, the same thing happened with each and everyone and they all went away. After that, the lice increased beyond limits, their throats choked and they could not even eat and drink, and they died within a period of two months.
Some died within five days and some in ten, some in less and some in more; but none lived for more than two months. On account of the scourge of lice and hunger they were all destroyed. This lice were sent by Allah as a divine sign on the enemies of His Holy Prophet (S).
Reference:Hayat Al-Qulub Vol. 2