Do these vermins trouble your head? He said: Yes. Thereupon he (the Holy Prophet) said: Shave your head. Then sacrifice a goat or observe fasts for three days or give three sits of dates to feed six needy persons.
Sahih Muslim Book 15, Hadith 92
← Previous Hadith Do these vermin trouble you? He (Ka'b) said: Yes. The Messenger of Allah (way peace be upon him) said: Shave your head and give some quantity of food enough to feed six needy persons (faraq is equal to three sa's), or observe fast for three days or offer sacrifice of a sacrificial animal. Ibn Najih (one of the narrators) said:" Or sacrifice a goat."

Sahih Muslim Book 15, Hadith 91 Next Hadith → I sat with Ka'b (Allah be pleased with him) and he was in the mosque. I asked him about this verse:" Compensation in (the form of) fasting, or Sadaqa or sacrifice." Ka'b (Allah be pleased with him) said: It was reveal- ed In my case. There was some trouble in my head. I was taken to the Messenger of Allah (ﷺ) and lice were creeping upon my face. Thereupon he said: I did not think that your trouble had become so unbearable as I see. Would you be able to afford (the sacrificing) of a goat? I (Ka'b) said: Then this verse was revealed:" Com- pensation (in the form of) fasting or alms or a sacrifice." He (the Holy Prophet) said: (It Implies) fasting for three days, or feeding six needy perscins, half sa' of food for every needy person. This verse was revealed particularly for me and (now) Its applica- tion is general for all of you.

Sahih Muslim Book 15, Hadith 93