Hadith.323 - Imam Jafar ibn Muhammad Al-Sadiq (as) said:
"Combing the hair removes ailments," referring specifically to fever.
In a narration by Ahmad ibn Abi Abdullah al-Barqi, it is stated: 'It removes fatigue,' meaning weakness.
Allah (swt), the Exalted, said:
'And do not slacken in My remembrance,' (Surah Taha 20:42) meaning do not become weak.