«حق لله على كل مسلم أن يغتسل في كل سبعة أيام يوما يغسل فيه رأسه وجسده»
The Prophet (peace and blessings be upon him) said:
"It is a right of Allah upon every Muslim that he takes a ritual bath (ghusl) one day in every seven days, in which he washes his head and his body."
Hadith Referenceصحیح الجامع الصغیر / حرف الحاء / 3154