Sahih Bukhari
Medicine
Volume: 007 / Book Number: 071 / Hadith Number: 620
Narrated Fatima bint Al-Mundhir:
Whenever a lady suffering from fever was brought to Asma' bint Abu Bakr, she used to invoke Allah for her and then sprinkle some water on her body, at the chest and say, "Allah's Apostle used to order us to abate fever with water."